MT48LC4M16A2TG-75:G TR - MICRON TECHNOLOGY

SDR SDRAM

MT48LC16M4A2 – 4 Meg x 4 x 4 Banks

MT48LC8M8A2 – 2 Meg x 8 x 4 Banks

MT48LC4M16A2 – 1 Meg x 16 x 4 Banks

Features

• PC100- and PC133-compliant

• Fully synchronous; all signals registered on positive

edge of system clock

• Internal, pipelined operation; column address can

be changed every clock cycle

• Internal banks for hiding row access/precharge

• Programmable burst lengths: 1, 2, 4, 8, or full-page

• Auto precharge, includes concurrent auto precharge

and auto refresh modes

• Self refresh modes: standard and low-power

(not available on AT devices)

• Auto refresh

– 64ms, 4096-cycle refresh

(commercial and industrial)

– 16ms, 4096-cycle refresh

(automotive)

• LVTTL-compatible inputs and outputs

• Single 3.3V ±0.3V power supply

Options Marking

• Configuration

– 16 Meg x 4 (4 Meg x 4 x 4 banks) 16M43

– 8 Meg x 8 (2 Meg x 8 x 4 banks) 8M8

– 4 Meg x 16 (1 Meg x 16 x 4 banks) 4M16

• Write recovery (tWR)

Options Marking

–tWR = 2 CLK A2

• Plastic package – OCPL1

– 54-pin TSOP II (400 mil) TG

– 54-pin TSOP II (400 mil) Pb-free P

– 54-ball VFBGA (x16 only) (8mm x

8mm)

– 54-ball VFBGA (x16 only) (8mm x

8mm)

B42

• Timing – cycle time

– 6ns @ CL = 3 (x16 only) -63

– 6ns @ CL = 3 -6A

– 7.5ns @ CL = 3 (PC133) -753

– 7.5ns @ CL = 2 (PC133) -7E

• Self refresh

– Standard None

– Low-power L3

• Operating temperature range

– Commercial (0˚C to +70˚C) None

– Industrial (–40˚C to +85˚C) IT

– Automotive (–40˚C to +105˚C) AT2

• Revision :G, :J

Notes: 1. Off-center parting line.

2. Contact Micron for availability.

3. Available only on Revision G.

Table 1: Key Timing Parameters

CL = CAS (READ) latency

Speed Grade

Clock

Frequency (MHz) Target tRCD-tRP-CL tRCD (ns) tRP (ns) CL (ns)

-6 167 3-3-3 18 18 18

-6A 167 3-3-3 18 18 18

-75 133 3-3-3 20 20 20

-7E 133 2-2-2 15 15 15

64Mb: x4, x8, x16 SDRAM

Features

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Products and specifications discussed herein are subject to change by Micron without notice.

Table 2: Address Table

Parameter 16 Meg x 4 8 Meg x 8 4 Meg x 16

Configuration 4 Meg x 4 x 4 banks 2 Meg x 8 x 4 banks 1 Meg x 16 x 4 banks

Refresh count 4K 4K 4K

Row addressing 4K A[11:0] 4K A[11:0] 4K A[11:0]

Bank addressing 4 BA[1:0] 4 BA[1:0] 4 BA[1:0]

Column addressing 1K A[9:0] 512 A[8:0] 256 A[7:0]

Table 3: 64Mb SDR Part Numbering

Part Numbers Architecture Package

MT48LC16M4A2TG 16 Meg x 4 54-pin TSOP II

MT48LC16M4A2P 16 Meg x 4 54-pin TSOP II

MT48LC8M8A2TG 8 Meg x 8 54-pin TSOP II

MT48LC8M8A2P 8 Meg x 8 54-pin TSOP II

MT48LC4M16A2TG 4 Meg x 16 54-pin TSOP II

MT48LC4M16A2P 4 Meg x 16 54-pin TSOP II

MT48LC4M16A2B414 Meg x 16 54-ball VFBGA

MT48LC4M16A2F414 Meg x 16 54-ball VFBGA

Note: 1. FBGA Device Decoder: www.micron.com/decoder.

64Mb: x4, x8, x16 SDRAM

Features

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Contents

General Description ......................................................................................................................................... 7

Automotive Temperature .............................................................................................................................. 7

Functional Block Diagrams ............................................................................................................................... 8

Pin and Ball Assignments and Descriptions ..................................................................................................... 11

Package Dimensions ....................................................................................................................................... 14

Temperature and Thermal Impedance ............................................................................................................ 16

Electrical Specifications .................................................................................................................................. 19

Electrical Specifications – IDD Parameters ........................................................................................................ 21

Electrical Specifications – AC Operating Conditions ......................................................................................... 23

Functional Description ................................................................................................................................... 27

Commands .................................................................................................................................................... 28

COMMAND INHIBIT .................................................................................................................................. 28

NO OPERATION (NOP) ............................................................................................................................... 29

LOAD MODE REGISTER (LMR) ................................................................................................................... 29

ACTIVE ...................................................................................................................................................... 29

READ ......................................................................................................................................................... 30

WRITE ....................................................................................................................................................... 31

PRECHARGE .............................................................................................................................................. 32

BURST TERMINATE ................................................................................................................................... 32

REFRESH ................................................................................................................................................... 33

AUTO REFRESH ..................................................................................................................................... 33

SELF REFRESH ....................................................................................................................................... 33

Truth Tables ................................................................................................................................................... 34

Initialization .................................................................................................................................................. 39

Mode Register ................................................................................................................................................ 41

Burst Length .............................................................................................................................................. 43

Burst Type .................................................................................................................................................. 43

CAS Latency ............................................................................................................................................... 45

Operating Mode ......................................................................................................................................... 45

Write Burst Mode ....................................................................................................................................... 45

Bank/Row Activation ...................................................................................................................................... 46

READ Operation ............................................................................................................................................. 47

WRITE Operation ........................................................................................................................................... 56

Burst Read/Single Write .............................................................................................................................. 63

PRECHARGE Operation .................................................................................................................................. 64

Auto Precharge ........................................................................................................................................... 64

AUTO REFRESH Operation ............................................................................................................................. 76

SELF REFRESH Operation ............................................................................................................................... 78

Power-Down .................................................................................................................................................. 80

Clock Suspend ............................................................................................................................................... 81

64Mb: x4, x8, x16 SDRAM

Features

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List of Figures

Figure 1: 16 Meg x 4 Functional Block Diagram ................................................................................................. 8

Figure 2: 8 Meg x 8 Functional Block Diagram ................................................................................................... 9

Figure 3: 4 Meg x 16 Functional Block Diagram ............................................................................................... 10

Figure 4: 54-Pin TSOP (Top View) .................................................................................................................. 11

Figure 5: 54-Ball VFBGA x16 (Top View) ......................................................................................................... 12

Figure 6: 54-Pin Plastic TSOP (400 mil) – Package Codes TG/P ......................................................................... 14

Figure 7: 54-Ball VFBGA (8mm x 8mm) – Package Codes F4/B4 ....................................................................... 15

Figure 8: Example: Temperature Test Point Location, 54-Pin TSOP (Top View) ................................................. 17

Figure 9: Example: Temperature Test Point Location, 54-Ball VFBGA (Top View) .............................................. 18

Figure 10: ACTIVE Command ........................................................................................................................ 29

Figure 11: READ Command ........................................................................................................................... 30

Figure 12: WRITE Command ......................................................................................................................... 31

Figure 13: PRECHARGE Command ................................................................................................................ 32

Figure 14: Initialize and Load Mode Register .................................................................................................. 40

Figure 15: Mode Register Definition ............................................................................................................... 42

Figure 16: CAS Latency .................................................................................................................................. 45

Figure 17: Example: Meeting tRCD (MIN) When 2 < tRCD (MIN)/tCK < 3 .......................................................... 46

Figure 18: Consecutive READ Bursts .............................................................................................................. 48

Figure 19: Random READ Accesses ................................................................................................................ 49

Figure 20: READ-to-WRITE ............................................................................................................................ 50

Figure 21: READ-to-WRITE With Extra Clock Cycle ......................................................................................... 51

Figure 22: READ-to-PRECHARGE .................................................................................................................. 51

Figure 23: Terminating a READ Burst ............................................................................................................. 52

Figure 24: Alternating Bank Read Accesses ..................................................................................................... 53

Figure 25: READ Continuous Page Burst ......................................................................................................... 54

Figure 26: READ – DQM Operation ................................................................................................................ 55

Figure 27: WRITE Burst ................................................................................................................................. 56

Figure 28: WRITE-to-WRITE .......................................................................................................................... 57

Figure 29: Random WRITE Cycles .................................................................................................................. 58

Figure 30: WRITE-to-READ ............................................................................................................................ 58

Figure 31: WRITE-to-PRECHARGE ................................................................................................................. 59

Figure 32: Terminating a WRITE Burst ............................................................................................................ 60

Figure 33: Alternating Bank Write Accesses ..................................................................................................... 61

Figure 34: WRITE – Continuous Page Burst ..................................................................................................... 62

Figure 35: WRITE – DQM Operation ............................................................................................................... 63

Figure 36: READ With Auto Precharge Interrupted by a READ ......................................................................... 65

Figure 37: READ With Auto Precharge Interrupted by a WRITE ........................................................................ 66

Figure 38: READ With Auto Precharge ............................................................................................................ 67

Figure 39: READ Without Auto Precharge ....................................................................................................... 68

Figure 40: Single READ With Auto Precharge .................................................................................................. 69

Figure 41: Single READ Without Auto Precharge ............................................................................................. 70

Figure 42: WRITE With Auto Precharge Interrupted by a READ ........................................................................ 71

Figure 43: WRITE With Auto Precharge Interrupted by a WRITE ...................................................................... 71

Figure 44: WRITE With Auto Precharge ........................................................................................................... 72

Figure 45: WRITE Without Auto Precharge ..................................................................................................... 73

Figure 46: Single WRITE With Auto Precharge ................................................................................................. 74

Figure 47: Single WRITE Without Auto Precharge ............................................................................................ 75

Figure 48: Auto Refresh Mode ........................................................................................................................ 77

Figure 49: Self Refresh Mode .......................................................................................................................... 79

Figure 50: Power-Down Mode ........................................................................................................................ 80

64Mb: x4, x8, x16 SDRAM

Features

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Figure 51: Clock Suspend During WRITE Burst ............................................................................................... 81

Figure 52: Clock Suspend During READ Burst ................................................................................................. 82

Figure 53: Clock Suspend Mode ..................................................................................................................... 83

64Mb: x4, x8, x16 SDRAM

Features

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List of Tables

Table 1: Key Timing Parameters ....................................................................................................................... 1

Table 2: Address Table ..................................................................................................................................... 2

Table 3: 64Mb SDR Part Numbering ................................................................................................................. 2

Table 4: Pin and Ball Descriptions .................................................................................................................. 13

Table 5: Temperature Limits .......................................................................................................................... 16

Table 6: Thermal Impedance Simulated Values ............................................................................................... 17

Table 7: Absolute Maximum Ratings .............................................................................................................. 19

Table 8: DC Electrical Characteristics and Operating Conditions ..................................................................... 19

Table 9: Capacitance ..................................................................................................................................... 20

Table 10: IDD Specifications and Conditions – Revision G ................................................................................ 21

Table 11: IDD Specifications and Conditions – Revision J ................................................................................. 21

Table 12: Electrical Characteristics and Recommended AC Operating Conditions ............................................ 23

Table 13: AC Functional Characteristics ......................................................................................................... 25

Table 14: Truth Table – Commands and DQM Operation ................................................................................. 28

Table 15: Truth Table – Current State Bank n, Command to Bank n .................................................................. 34

Table 16: Truth Table – Current State Bank n, Command to Bank m ................................................................. 36

Table 17: Truth Table – CKE ........................................................................................................................... 38

Table 18: Burst Definition Table ..................................................................................................................... 44

64Mb: x4, x8, x16 SDRAM

Features

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General Description

The 64Mb SDRAM is a high-speed CMOS, dynamic random-access memory containing

67,108,864 bits. It is internally configured as a quad-bank DRAM with a synchronous in-

terface (all signals are registered on the positive edge of the clock signal, CLK). Each of

the x4’s 16,777,216-bit banks is organized as 4096 rows by 1024 columns by 4 bits. Each

of the x8’s 16,777,216-bit banks is organized as 4096 rows by 512 columns by 8 bits. Each

of the x16’s 16,777,216-bit banks is organized as 4096 rows by 256 columns by 16 bits.

Read and write accesses to the SDRAM are burst-oriented; accesses start at a selected

location and continue for a programmed number of locations in a programmed se-

quence. Accesses begin with the registration of an ACTIVE command, which is then fol-

lowed by a READ or WRITE command. The address bits registered coincident with the

ACTIVE command are used to select the bank and row to be accessed (BA[1:0] select the

bank; A[11:0] select the row). The address bits registered coincident with the READ or

WRITE command are used to select the starting column location for the burst access.

The SDRAM provides for programmable read or write burst lengths (BL) of 1, 2, 4, or 8

locations, or the full page, with a burst terminate option. An auto precharge function

may be enabled to provide a self-timed row precharge that is initiated at the end of the

burst sequence.

The 64Mb SDRAM uses an internal pipelined architecture to achieve high-speed opera-

tion. This architecture is compatible with the 2n rule of prefetch architectures, but it al-

so allows the column address to be changed on every clock cycle to achieve a high-

speed, fully random access. Precharging one bank while accessing one of the other

three banks will hide the PRECHARGE cycles and provide seamless, high-speed, ran-

dom-access operation.

The 64Mb SDRAM is designed to operate in 3.3V memory systems. An auto refresh

mode is provided, along with a power-saving, power-down mode. All inputs and out-

puts are LVTTL-compatible.

SDRAM devices offer substantial advances in DRAM operating performance, including

the ability to synchronously burst data at a high data rate with automatic column-ad-

dress generation, the ability to interleave between internal banks to hide precharge

time, and the capability to randomly change column addresses on each clock cycle dur-

ing a burst access.

Automotive Temperature

The automotive temperature (AT) option adheres to the following specifications:

• 16ms refresh rate

• Self refresh not supported

• Ambient and case temperature cannot be less than –40°C or greater than +105°C

64Mb: x4, x8, x16 SDRAM

General Description

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Functional Block Diagrams

Figure 1: 16 Meg x 4 Functional Block Diagram

RAS#

CAS#

Row-

address

MUX

CLK

CS#

WE#

CKE Control logic

Column

address

counter/

latch

Mode register

Command

decode

A[11:0],

BA0, BA1

DQM

Address

1024

(x4)

4096

I/O gating

DQM mask logic

read data latch

write drivers

Column

decoder

Bank 0

memory

array

(4096 x 1024 x 4)

Bank 0

row-

address

latch

and

decoder

4096

Sense amplifiers

Bank

control

logic

DQ[3:0]

Data

input

Data

output

Bank 1

Bank 2Bank 3

1 1

Refresh

counter

64Mb: x4, x8, x16 SDRAM

Functional Block Diagrams

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Figure 2: 8 Meg x 8 Functional Block Diagram

RAS#

CAS#

Row-

address

MUX

CLK

CS#

WE#

CKE Control logic

Column-

address

counter/

latch

Mode register

Command

decode

A[11:0],

BA0, BA1

DQM

Address

512

(x8)

4096

I/O gating

DQM mask logic

read data latch

write drivers

Column

decoder

Bank 0

memory

array

(4096 x 512 x 8)

Bank 0

row-

address

latch

and

decoder

4096

Sense amplifiers

Bank

control

logic

DQ[7:0]

Data

input

Data

output

Bank 1

Bank 2

Bank 3

1 1

Refresh

counter

64Mb: x4, x8, x16 SDRAM

Functional Block Diagrams

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Figure 3: 4 Meg x 16 Functional Block Diagram

RAS#

CAS#

Row-

address

MUX

CLK

CS#

WE#

CKE

Column-

address

counter/

latch

A[11:0],

BA0, BA1

DQML,

DQMH

Address

256

(x16)

4096

I/O gating

DQM mask logic

read data latch

write drivers

Column

decoder

Bank 0

memory

array

(4096 x 256 x 16)

Bank 0

row-

address

latch

and

decoder

4096

Sense amplifiers

Bank

control

logic

DQ[15:0]

Data

input

Data

output

Bank 1

Bank 2

Bank 3

2 2

Refresh

counter

Control logic

Mode register

Command

decode

64Mb: x4, x8, x16 SDRAM

Functional Block Diagrams

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Pin and Ball Assignments and Descriptions

Figure 4: 54-Pin TSOP (Top View)

VDD

DQ0

VDDQ

DQ1

DQ2

VSSQ

DQ3

DQ4

VDDQ

DQ5

DQ6

VSSQ

DQ7

VDD

DQML

WE#

CAS#

RAS#

CS#

BA0

BA1

A10

VDD

VSS

DQ15

VSSQ

DQ14

DQ13

VDDQ

DQ12

DQ11

VSSQ

DQ10

DQ9

VDDQ

DQ8

VSS

DQMH

CLK

CKE

A11

VSS

x8x16 x16x8 x4x4

–

DQ0

–

DQ1

–

DQ2

–

DQ3

–

DQ0

–

DQ1

–

DQ7

–

DQ6

–

DQ5

–

DQ4

–

DQM

–

DQ3

–

DQ2

–

DQM

–

Notes: 1. A dash (–) indicates that the x8 and x4 pin function is the same as the x16 pin function.

2. Package may or may not be assembled with a location notch.

64Mb: x4, x8, x16 SDRAM

Pin and Ball Assignments and Descriptions

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Figure 5: 54-Ball VFBGA x16 (Top View)

1 2 3 4 5 6 7 8

Top View

(Ball Down)

VSS

DQ14

DQ12

DQ10

DQ8

DQMH

NC/A12

DQ15

DQ13

DQ11

DQ9

CLK

A11

VSSQ

VDDQ

VDDQ VDD

VDDQ

VSS

VSS VDD

VDD

CKE

CAS#

BA0

DQ0

DQ2

DQ4

DQ6

DQML

RAS#

BA1

DQ1

DQ3

DQ5

DQ7

WE#

CS#

A10

Note: 1. The balls at A4, A5, and A6 are absent from the physical package. They are included to

illustrate that rows 4, 5, and 6 exist, but contain no solder balls.

64Mb: x4, x8, x16 SDRAM

Pin and Ball Assignments and Descriptions

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Table 4: Pin and Ball Descriptions

Symbol Type Description

CLK Input Clock: CLK is driven by the system clock. All SDRAM input signals are sampled on the positive

edge of CLK. CLK also increments the internal burst counter and controls the output registers.

CKE Input Clock enable: CKE activates (HIGH) and deactivates (LOW) the CLK signal. Deactivating the

clock provides precharge power-down and SELF REFRESH operation (all banks idle), active

power-down (row active in any bank), or CLOCK SUSPEND operation (burst/access in pro-

gress). CKE is synchronous except after the device enters power-down and self refresh modes,

where CKE becomes asynchronous until after exiting the same mode. The input buffers, in-

cluding CLK, are disabled during power-down and self refresh modes, providing low standby

power. CKE may be tied HIGH.

CS# Input Chip select: CS# enables (registered LOW) and disables (registered HIGH) the command de-

coder. All commands are masked when CS# is registered HIGH, but READ/WRITE bursts already

in progress will continue, and DQM operation will retain its DQ mask capability while CS# is

HIGH. CS# provides for external bank selection on systems with multiple banks. CS# is consid-

ered part of the command code.

CAS#, RAS#,

WE#

Input Command inputs: RAS#, CAS#, and WE# (along with CS#) define the command being en-

tered.

x4, x8:

DQM

x16:

DQML, DQMH

Input Input/output mask: DQM is sampled HIGH and is an input mask signal for write accesses and

an output enable signal for read accesses. Input data is masked during a WRITE cycle. The

output buffers are High-Z (two-clock latency) during a READ cycle. On the x4 and x8, DQML

(pin 15) is NC; DQMH is DQM. On the x16, DQML corresponds to DQ[7:0] and DQMH corre-

sponds to DQ[15:8]. DQML and DQMH are considered same-state when referenced as DQM.

BA[1:0] Input Bank address input(s): BA[1:0] define to which bank the ACTIVE, READ, WRITE, or PRE-

CHARGE command is being applied.

A[11:0] Input Address inputs: A[11:0] are sampled during the ACTIVE command (row address A[11:0]) and

READ or WRITE command (column address A[9:0] for x4; A[8:0] for x8; A[7:0] for x16; with

A10 defining auto precharge) to select one location out of the memory array in the respective

bank. A10 is sampled during a PRECHARGE command to determine whether all banks are to

be precharged (A10 HIGH) or bank selected by BA[1:0] (A1 LOW). The address inputs also pro-

vide the op-code during a LOAD MODE REGISTER command.

x16:

DQ[15:0]

I/O Data input/output: Data bus for x16 (pins 4, 7, 10, 13, 42, 45, 48, and 51 are NC for x8; and

pins 2, 4, 7, 8, 10, 13, 42, 45, 47, 48, 51, and 53 are NC for x4).

x8:

DQ[7:0]

I/O Data input/output: Data bus for x8 (pins 2, 8, 47, 53 are NC for x4).

x4:

DQ[3:0]

I/O Data input/output: Data bus for x4.

VDDQ Supply DQ power: DQ power to the die for improved noise immunity.

VSSQ Supply DQ ground: DQ ground to the die for improved noise immunity.

VDD Supply Power supply: 3.3V ±0.3V.

VSS Supply Ground.

NC – No connect: These should be left unconnected.

64Mb: x4, x8, x16 SDRAM

Pin and Ball Assignments and Descriptions

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Package Dimensions

Figure 6: 54-Pin Plastic TSOP (400 mil) – Package Codes TG/P

See Detail A

0.10 +0.10

-0.05

0.15 +0.03

-0.02

2X R 1.00

2X R 0.75

0.80 TYP

(for reference only)

2X 0.71

0.50 ±0.10

Pin #1 ID

Detail A

22.22 ±0.08

10.16 ±0.08

11.76 ±0.20

0.375 ±0.075 TYP

1.2 MAX

0.25

0.80

2X 0.10

2.80 Gage plane

Plated lead finish: 90% Sn, 10% Pb or 100% Sn

Plastic package material: Epoxy novolac

Package width and length do not include

mold protrusion. Allowable protrusion is

0.25 per side.

0.10

Notes: 1. All dimensions are in millimeters.

2. Package width and length do not include mold protrusion; allowable mold protrusion is

0.25mm per side.

3. Package may or may not be assembled with a location notch.

64Mb: x4, x8, x16 SDRAM

Package Dimensions

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Figure 7: 54-Ball VFBGA (8mm x 8mm) – Package Codes F4/B4

Ball A1 ID

0.65 ±0.05

Seating plane

0.10 C

1.00 MAX

Ball A9

0.80

TYP

0.80 TYP

3.20

6.40

8.00 ±0.10

4.00 ±0.05

Solder ball

diameter refers

to post reflow

condition. The pre-

reflow diameter

is 0.42.

54X Ø0.45 ±0.05

Solder ball material:

62% Sn, 36% Pb, 2% Ag or

96.5% Sn, 3% Ag, 0.5% Cu

Solder mask defined ball pads:

Ø0.40

Mold compound: Epoxy novolac

Substrate material: Plastic laminate

6.40

3.20

4.00 ±0.05

8.00 ±0.10

Ball A1 ID

Ball A1

Notes: 1. All dimensions are in millimeters.

2. Recommended pad size = Ø 0.4mm SMD.

64Mb: x4, x8, x16 SDRAM

Package Dimensions

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Temperature and Thermal Impedance

It is imperative that the SDRAM device’s temperature specifications, shown in Temper-

ature Limits below, be maintained to ensure the junction temperature is in the proper

operating range to meet data sheet specifications. An important step in maintaining the

proper junction temperature is using the device’s thermal impedances correctly. The

thermal impedances are listed in Table 6 (page 17) for the applicable die revision and

packages being made available. These thermal impedance values vary according to the

density, package, and particular design used for each device.

Incorrectly using thermal impedances can produce significant errors. Read Micron

technical note TN-00-08, “Thermal Applications” prior to using the thermal impedan-

ces listed in Table 6 (page 17). To ensure the compatibility of current and future de-

signs, contact Micron Applications Engineering to confirm thermal impedance values.

The SDRAM device’s safe junction temperature range can be maintained when the TC

specification is not exceeded. In applications where the device’s ambient temperature

is too high, use of forced air and/or heat sinks may be required to satisfy the case tem-

perature specifications.

Table 5: Temperature Limits

Parameter Symbol Min Max Unit Notes

Operating case temperature Commercial TC0 80 °C 1, 2, 3, 4

Industrial –40 90

Automotive –40 105

Junction temperature Commercial TJ0 85 °C 3

Industrial –40 95

Automotive –40 110

Ambient temperature Commercial TA0 70 °C 3, 5

Industrial –40 85

Automotive –40 105

Peak reflow temperature TPEAK – 260 °C

Notes: 1. MAX operating case temperature, TC, is measured in the center of the package on the

top side of the device, as shown in Figure 8 (page 17), and Figure 9 (page 18).

2. Device functionality is not guaranteed if the device exceeds maximum TC during opera-

tion.

3. All temperature specifications must be satisfied.

4. The case temperature should be measured by gluing a thermocouple to the top-center

of the component. This should be done with a 1mm bead of conductive epoxy, as de-

fined by the JEDEC EIA/JESD51 standards. Take care to ensure that the thermocouple

bead is touching the case.

5. Operating ambient temperature surrounding the package.

64Mb: x4, x8, x16 SDRAM

Temperature and Thermal Impedance

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Table 6: Thermal Impedance Simulated Values

Die

Revision Package Substrate

Θ JA (°C/W)

Airflow =

0m/s

Θ JA (°C/W)

Airflow =

1m/s

Θ JA (°C/W)

Airflow =

2m/s Θ JB (°C/W) Θ JC (°C/W)

G 54-pin TSOP High Con-

ductivity

70.5 61.2 57.2 54.6 13.7

54-ball VFBGA Low Con-

ductivity

80.6 67.7 61.5 46.1 4.9

High Con-

ductivity

63.96 57.1 53.5 45.7

J 54-pin TSOP Low Con-

ductivity

122.3 105.6 98.1 89.5 20.7

High Con-

ductivity

101.9 93.5 88.8 87.6

54-ball VFBGA Low Con-

ductivity

96.9 81.9 81.9 69.5 11.5

High Con-

ductivity

74.0 66.3 62.7 60.7

Notes: 1. For designs expected to last beyond the die revision listed, contact Micron Applications

Engineering to confirm thermal impedance values.

2. Thermal resistance data is sampled from multiple lots, and the values should be viewed

as typical.

3. These are estimates; actual results may vary.

Figure 8: Example: Temperature Test Point Location, 54-Pin TSOP (Top View)

22.22mm

11.11mm

Test point

10.16mm

5.08mm

Note: 1. Package may or may not be assembled with a location notch.

64Mb: x4, x8, x16 SDRAM

Temperature and Thermal Impedance

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Figure 9: Example: Temperature Test Point Location, 54-Ball VFBGA (Top View)

8.00mm

4.00mm

Test point

4.00mm

8.00mm

64Mb: x4, x8, x16 SDRAM

Temperature and Thermal Impedance

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Electrical Specifications

Stresses greater than those listed may cause permanent damage to the device. This is a

stress rating only, and functional operation of the device at these or any other condi-

tions above those indicated in the operational sections of this specification is not im-

plied. Exposure to absolute maximum rating conditions for extended periods may affect

reliability.

Table 7: Absolute Maximum Ratings

Voltage/Temperature Symbol Min Max Unit

Voltage on VDD/VDDQ supply relative to VSS VDD/VDDQ –1 4.6 V

Voltage on inputs, NC, or I/O balls relative to VSS VIN –1 4.6

Storage temperature (plastic) TSTG –55 150 °C

Power dissipation – – 1 W

Table 8: DC Electrical Characteristics and Operating Conditions

Notes 1–3 apply to all parameters and conditions; VDD/VDDQ = 3.3V ±0.3V

Parameter/Condition Symbol Min Max Unit Notes

Supply voltage VDD, VDDQ 3 3.6 V

Input high voltage: Logic 1; All inputs VIH 2 VDD + 0.3 V 4

Input low voltage: Logic 0; All inputs VIL –0.3 0.8 V 4

Output high voltage: IOUT = –4mA VOH 2.4 – V

Output low voltage: IOUT = 4mA VOL – 0.4 V

Input leakage current:

Any input 0V ≤ VIN ≤ VDD (All other balls not under test = 0V)

IL–5 5 μA

Output leakage current: DQ are disabled; 0V ≤ VOUT ≤ VDDQ IOZ –5 –5 μA

Operating temperature: Commercial TA0 70 ˚C

Industrial TA–40 85 ˚C

Automotive TA–40 105 ˚C

Notes: 1. All voltages referenced to VSS.

2. The minimum specifications are used only to indicate cycle time at which proper opera-

tion over the full temperature range is ensured; (0°C ≤ TA ≤ +70°C (commercial), –40°C ≤

TA ≤ +85°C (industrial), and –40°C ≤ TA ≤ +105°C (automotive)).

3. An initial pause of 100μs is required after power-up, followed by two AUTO REFRESH

commands, before proper device operation is ensured. (VDD and VDDQ must be powered

up simultaneously. VSS and VSSQ must be at same potential.) The two AUTO REFRESH

command wake-ups should be repeated any time the tREF refresh requirement is excee-

ded.

4. VIH overshoot: VIH,max = VDDQ + 2V for a pulse width ≤3ns, and the pulse width cannot

be greater than one-third of the cycle rate. VIL undershoot: VIL,min = –2V for a pulse

width ≤3ns.

64Mb: x4, x8, x16 SDRAM

Electrical Specifications

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Table 9: Capacitance

Note 1 applies to all parameters and conditions

Package Parameter Symbol Min Max Unit Notes

TSOP package Input capacitance: CLK CL1 2.5 3.5 pF 2

Input capacitance: All other input-only

balls

CL2 2.5 3.8 pF 3

Input/output capacitance: DQ CL0 4 6 pF 4

VFBGA package Input capacitance: CLK CL1 1.5 3.5 pF 2

Input capacitance: All other input-only

balls

CL2 1.5 3.8 pF 3

Input/output capacitance: DQ CL0 3 6 pF 4

Notes: 1. This parameter is sampled. VDD, VDDQ = 3.3V; f = 1 MHz, TA = 25°C; pin under test biased

at 1.4V.

2. PC100 specifies a maximum of 4pF.

3. PC100 specifies a maximum of 5pF.

4. PC100 specifies a maximum of 6.5pF.

64Mb: x4, x8, x16 SDRAM

Electrical Specifications

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Electrical Specifications – IDD Parameters

Table 10: IDD Specifications and Conditions – Revision G

Notes 1–3 apply to all parameters and conditions; VDD/VDDQ = 3.3V ±0.3V

Parameter/Condition Symbol

Max

Unit Notes-6 -7E -75

Operating current: Active mode; Burst = 2; READ or WRITE;

tRC ≥ tRC (MIN)

IDD1 150 125 115 mA 4, 5, 6, 7

Standby current: Power-down mode; All banks idle; CKE =

LOW

IDD2 2 2 2 mA 7

Standby current: Active mode; CKE = HIGH; CS# = HIGH; All

banks active after tRCD met; No accesses in progress

IDD3 60 45 45 mA 4, 6, 7, 8

Operating current: Burst mode; Page burst; READ or WRITE;

All banks active

IDD4 180 150 140 mA 4, 5, 6, 7

Auto refresh current: CKE = HIGH; CS# =

HIGH

tRFC = tRFC (MIN) IDD5 250 230 210 mA 4, 5, 6, 7,

8, 9tRFC = 15.625μs IDD6 3 3 3 mA

tRFC = 3.906μs

(AT)

IDD6 6 6 6 mA

Self refresh current: CKE ≤ 0.2V Standard IDD7 1 1 1 mA 10

Low power (L) IDD7 0.5 0.5 0.5 mA

Table 11: IDD Specifications and Conditions – Revision J

Notes 1–3 apply to all parameters and conditions; VDD/VDDQ = 3.3V ±0.3V

Parameter/Condition Symbol

Max

Unit Notes-6A -7E -75

Operating current: Active mode; Burst = 2; READ or WRITE;

tRC ≥ tRC (MIN)

IDD1 100 100 100 mA 4, 5, 6, 7

Standby current: Power-down mode; All banks idle; CKE =

LOW

IDD2 2.5 2.5 2.5 mA 7

Standby current: Active mode; CKE = HIGH; CS# = HIGH; All

banks active after tRCD met; No accesses in progress

IDD3 35 35 35 mA 4, 6, 7, 8

Operating current: Burst mode; Page burst; READ or WRITE;

All banks active

IDD4 100 100 100 mA 4, 5, 6, 7

Auto refresh current: CKE = HIGH; CS# =

HIGH

tRFC = tRFC (MIN) IDD5 150 150 150 mA 4, 5, 6, 7,

8, 9tRFC = 15.625μs IDD6 4 4 4 mA

tRFC = 3.906μs

(AT)

IDD6 6 6 6 mA

Self refresh current: CKE ≤ 0.2V Standard IDD7 3 3 3 mA 10

Notes: 1. All voltages referenced to VSS.

2. Minimum specifications are used only to indicate cycle time at which proper operation

over the full temperature range is ensured:

0°C ≤ TA ≤ +70°C (commercial)

–40°C ≤ TA ≤ +85°C (industrial)

64Mb: x4, x8, x16 SDRAM

Electrical Specifications – IDD Parameters

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–40°C ≤ TA ≤ +105°C (automotive)

3. An initial pause of 100μs is required after power-up, followed by two AUTO REFRESH

commands, before proper device operation is ensured. (VDD and VDDQ must be powered

up simultaneously. VSS and VSSQ must be at same potential.) The two AUTO REFRESH

command wake-ups should be repeated any time the tREF refresh requirement is excee-

ded.

4. IDD is dependent on output loading and cycle rates. Specified values are obtained with

minimum cycle time and the outputs open.

5. The IDD current will increase or decrease proportionally according to the amount of fre-

quency alteration for the test condition.

6. Address transitions average one transition every two clocks.

7. For -75, CL = 3 and tCK = 7.5ns; for -7E, CL = 2 and tCK = 7.5ns; for -6, CL = 3 and tCK =

6ns.

8. Other input signals are allowed to transition no more than once every two clocks and

are otherwise at valid VIH or VIL levels.

9. CKE is HIGH during refresh command period tRFC (MIN) else CKE is LOW. The IDD6 limit is

actually a nominal value and does not result in a fail value.

10. Enables on-chip refresh and address counters.

64Mb: x4, x8, x16 SDRAM

Electrical Specifications – IDD Parameters

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Electrical Specifications – AC Operating Conditions

Table 12: Electrical Characteristics and Recommended AC Operating Conditions

Notes 1–6 apply to all parameters and conditions

Parameter Symbol

-6 -6A -7E -75

Unit NotesMin Max Min Max Min Max Min Max

Access time from

CLK (positive

edge)

CL = 3 tAC(3) – 5.5 – 5.4 – 5.4 – 5.4 ns 8

CL = 2 tAC(2) – 7.5 – 7.57– 5.4 – 6 ns 8

CL = 1 tAC(1) – 17 – 177– – – – ns 8

Address hold time tAH 1 – 0.8 – 0.8 – 0.8 – ns

Address setup time tAS 1.5 – 1.5 – 1.5 – 1.5 – ns

CLK high-level width tCH 2.5 – 2.5 – 2.5 – 2.5 – ns

CLK low-level width tCL 2.5 – 2.5 – 2.5 – 2.5 – ns

Clock cycle time CL = 3 tCK(3) 6 – 6 – 7 – 7.5 – ns 9

CL = 2 tCK(2) 10 – 107– 7.5 – 10 – ns 9

CL = 1 tCK(1) 20 – 207– – – – – ns 9

CKE hold time tCKH 1 – 0.8 – 0.8 – 0.8 – ns

CKE setup time tCKS 1.5 – 1.5 – 1.5 – 1.5 – ns

CS#, RAS#, CAS#, WE#,

DQM hold time

tCMH 1 – 0.8 0.8 – 0.8 – ns

CS#, RAS#, CAS#, WE#,

DQM setup time

tCMS 1.5 – 1.5 – 1.5 – 1.5 – ns

Data-in hold time tDH 1 – 0.8 – 0.8 – 0.8 – ns

Data-in setup time tDS 1.5 – 1.5 – 1.5 – 1.5 – ns

Data-out High-Z

time

CL = 3 tHZ(3) – 5.5 – 5.4 – 5.4 – 5.4 ns 10

CL = 2 tHZ(2) – 7.5 – 7.57– 5.4 – 6 ns 10

CL = 1 tHZ(1) – 17 – 177– – – – ns 10

Data-out Low-Z time tLZ 1 – 1 – 1 – 1 – ns

Data-out hold time (load) tOH 2 – 3 – 3 – 3 – ns

Data-out hold time (no

load)

tOHn1.8 – 1.8 – 1.8 – 1.8 – ns 11

ACTIVE-to-PRECHARGE

command

tRAS 42 120,00

42 120,00

37 120,00

44 120,00

ACTIVE-to-ACTIVE com-

mand period

tRC 60 – 60 – 60 – 66 – ns 12

ACTIVE-to-READ or WRITE

delay

tRCD 18 – 18 – 15 – 20 – ns

Refresh period (4096

rows)

tREF – 64 – 64 – 64 – 64 ms

Refresh period – automo-

tive (4096 rows)

tREFAT – 16 – 16 – 16 – 16 ms

AUTO REFRESH period tRFC 60 – 60 – 66 – 66 – ns

64Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

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Table 12: Electrical Characteristics and Recommended AC Operating Conditions (Continued)

Notes 1–6 apply to all parameters and conditions

Parameter Symbol

-6 -6A -7E -75

Unit NotesMin Max Min Max Min Max Min Max

PRECHARGE command

period

tRP 18 – 18 – 15 – 20 – ns

ACTIVE bank a to ACTIVE

bank b command

tRRD 12 – 12 – 14 – 15 – ns

Transition time tT 0.3 1.2 0.3 1.2 0.3 1.2 0.3 1.2 ns 13

WRITE recovery time tWR 1 CLK +

6ns

– 1 CLK +

6ns

– 1 CLK +

7ns

– 1 CLK +

7.5ns

– ns 14

12 – 12 – 14 – 15 – 15

Exit SELF REFRESH-to-AC-

TIVE command

tXSR 70 – 67 – 67 – 75 – ns 16

64Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

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Table 13: AC Functional Characteristics

Notes 1–6 apply to all parameters and conditions

Parameter Symbol -6/-6A -7E -75 Unit

Note

Last data-in to burst STOP command tBDL 1 1 1 tCK 17

READ/WRITE command to READ/WRITE command tCCD 1 1 1 tCK 17

Last data-in to new READ/WRITE command tCDL 1 1 1 tCK 17

CKE to clock disable or power-down entry mode tCKED 1 1 1 tCK 18

Data-in to ACTIVE command tDAL 5 4 5 tCK 19,

Data-in to PRECHARGE command tDPL 2 2 2 tCK 20,

DQM to input data delay tDQD 0 0 0 tCK 17

DQM to data mask during WRITEs tDQM 0 0 0 tCK 17

DQM to data High-Z during READs tDQZ 2 2 2 tCK 17

WRITE command to input data delay tDWD 0 0 0 tCK 17

LOAD MODE REGISTER command to ACTIVE or REFRESH command tMRD 2 2 2 tCK 22

CKE to clock enable or power-down exit setup mode tPED 1 1 1 tCK 17

Last data-in to PRECHARGE command tRDL 2 2 2 tCK 20,

Data-out High-Z from PRECHARGE command CL = 3 tROH(3) 3 3 3 tCK 17

CL = 2 tROH(2) 2 2 2 tCK 17

CL = 1 tROH(1) 1 – – tCK 17

Notes: 1. Minimum specifications are used only to indicate cycle time at which proper operation

over the full temperature range is ensured:

0°C ≤ TA ≤ +70°C (commercial)

–40°C ≤ TA ≤ +85°C (industrial)

–40°C ≤ TA ≤ +105°C (automotive)

2. An initial pause of 100μs is required after power-up, followed by two AUTO REFRESH

commands, before proper device operation is ensured. (VDD and VDDQ must be powered

up simultaneously. VSS and VSSQ must be at same potential.) The two AUTO REFRESH

command wake-ups should be repeated any time the tREF refresh requirement is excee-

ded.

3. In addition to meeting the transition rate specification, the clock and CKE must transit

between VIH and VIL (or between VIL and VIH) in a monotonic manner.

4. Outputs measured at 1.5V with equivalent load:

50pF

5. AC operating and IDD test conditions have VIL = 0V and VIH = 3.0V using a measurement

reference level of 1.5V. If the input transition time is longer than 1ns, then the timing is

measured from VIL,max and VIH,min and no longer from the 1.5V midpoint. CLK should al-

ways be 1.5V referenced to crossover. Refer to Micron technical note TN-48-09.

6. The -6 speed grade does not support CL = 2.

7. Not applicable for Revision G.

64Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

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8. tAC for -75/-7E at CL = 3 with no load is 4.6ns and is guaranteed by design.

9. The clock frequency must remain constant (stable clock is defined as a signal cycling

within timing constraints specified for the clock pin) during access or precharge states

(READ, WRITE, including tWR, and PRECHARGE commands). CKE may be used to reduce

the data rate.

10. tHZ defines the time at which the output achieves the open circuit condition; it is not a

reference to VOH or VOL. The last valid data element will meet tOH before going High-Z.

11. Parameter guaranteed by design.

12. DRAM devices should be evenly addressed when being accessed. Disproportionate ac-

cesses to a particular row address may result in reduction of the product lifetime.

13. AC characteristics assume tT = 1ns.

14. Auto precharge mode only. The precharge timing budget (tRP) begins at 6ns for -6, at

7ns for -7E, and 7.5ns for -75 after the first clock delay and after the last WRITE is execu-

ted.

15. Precharge mode only.

16. CLK must be toggled a minimum of two times during this period.

17. Required clocks are specified by JEDEC functionality and are not dependent on any tim-

ing parameter.

18. Timing specified by tCKS. Clock(s) specified as a reference only at minimum cycle rate.

19. Timing is specified by tWR plus tRP. Clock(s) specified as a reference only at minimum cy-

cle rate.

20. Based on tCK = 7.5ns for -75 and -7E, 6ns for -6.

21. Timing is specified by tWR.

22. JEDEC and PC100 specify three clocks.

64Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

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Functional Description

In general, 64Mb SDRAM devices (4 Meg x 4 x 4 banks, 2 Meg x 8 x 4 banks, and 1 Meg x

16 x 4 banks) are quad-bank DRAM that operate at 3.3V and include a synchronous in-

terface. All signals are registered on the positive edge of the clock signal, CLK. Each of

the x4’s 16,777,216-bit banks is organized as 4096 rows by 1024 columns by 4 bits. Each

of the x8’s 16,777,216-bit banks is organized as 4096 rows by 512 columns by 8 bits. Each

of the x16’s 16,777,216-bit banks is organized as 4096 rows by 256 columns by 16 bits.

Read and write accesses to the SDRAM are burst-oriented; accesses start at a selected

location and continue for a programmed number of locations in a programmed se-

quence. Accesses begin with the registration of an ACTIVE command, followed by a

READ or WRITE command. The address bits registered coincident with the ACTIVE

command are used to select the bank and row to be accessed (BA0 and BA1 select the

bank, A[11:0] select the row). The address bits (x4: A[9:0]; x8: A[8:0]; x16: A[7:0]) regis-

tered coincident with the READ or WRITE command are used to select the starting col-

umn location for the burst access.

Prior to normal operation, the device must be initialized. The following sections provide

detailed information covering device initialization, register definition, command de-

scriptions, and device operation.

64Mb: x4, x8, x16 SDRAM

Functional Description

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Commands

The following table provides a quick reference of available commands, followed by a

written description of each command. Additional Truth Tables (Table 15 (page 34), Ta-

ble 16 (page 36), and Table 17 (page 38)) provide current state/next state informa-

tion.

Table 14: Truth Table – Commands and DQM Operation

Note 1 applies to all parameters and conditions

Name (Function) CS# RAS# CAS# WE# DQM ADDR DQ Notes

COMMAND INHIBIT (NOP) H X X X X X X

NO OPERATION (NOP) L H H H X X X

ACTIVE (select bank and activate row) L L H H X Bank/row X 2

READ (select bank and column, and start READ burst) L H L H L/H Bank/col X 3

WRITE (select bank and column, and start WRITE burst) L H L L L/H Bank/col Valid 3

BURST TERMINATE L H H L X X Active 4

PRECHARGE (Deactivate row in bank or banks) L L H L X Code X 5

AUTO REFRESH or SELF REFRESH (enter self refresh mode) L L L H X X X 6, 7

LOAD MODE REGISTER L L L L X Op-code X 8

Write enable/output enable X X X X L X Active 9

Write inhibit/output High-Z X X X X H X High-Z 9

Notes: 1. CKE is HIGH for all commands shown except SELF REFRESH.

2. A[0:n] provide row address (where An is the most significant address bit), BA0 and BA1

determine which bank is made active.

3. A[0:i] provide column address (where i = the most significant column address for a given

device configuration). A10 HIGH enables the auto precharge feature (nonpersistent),

while A10 LOW disables the auto precharge feature. BA0 and BA1 determine which

bank is being read from or written to.

4. The purpose of the BURST TERMINATE command is to stop a data burst, thus the com-

mand could coincide with data on the bus. However, the DQ column reads a “Don’t

Care” state to illustrate that the BURST TERMINATE command can occur when there is

no data present.

5. A10 LOW: BA0, BA1 determine the bank being precharged. A10 HIGH: all banks pre-

charged and BA0, BA1 are “Don’t Care.”

6. This command is AUTO REFRESH if CKE is HIGH, SELF REFRESH if CKE is LOW.

7. Internal refresh counter controls row addressing; all inputs and I/Os are “Don’t Care” ex-

cept for CKE.

8. A[11:0] define the op-code written to the mode register.

9. Activates or deactivates the DQ during WRITEs (zero-clock delay) and READs (two-clock

delay).

COMMAND INHIBIT

The COMMAND INHIBIT function prevents new commands from being executed by

the device, regardless of whether the CLK signal is enabled. The device is effectively de-

selected. Operations already in progress are not affected.

64Mb: x4, x8, x16 SDRAM

Commands

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NO OPERATION (NOP)

The NO OPERATION (NOP) command is used to perform a NOP to the selected device

(CS# is LOW). This prevents unwanted commands from being registered during idle or

wait states. Operations already in progress are not affected.

LOAD MODE REGISTER (LMR)

The mode registers are loaded via inputs A[n:0] (where An is the most significant ad-

dress term), BA0, and BA1(see Mode Register (page 41)). The LOAD MODE REGISTER

command can only be issued when all banks are idle and a subsequent executable com-

mand cannot be issued until tMRD is met.

ACTIVE

The ACTIVE command is used to activate a row in a particular bank for a subsequent

access. The value on the BA0, BA1 inputs selects the bank, and the address provided se-

lects the row. This row remains active for accesses until a PRECHARGE command is is-

sued to that bank. A PRECHARGE command must be issued before opening a different

row in the same bank.

Figure 10: ACTIVE Command

CS#

WE#

CAS#

RAS#

CKE

CLK

Address Row address

Don’t Care

HIGH

BA0, BA1 Bank address

64Mb: x4, x8, x16 SDRAM

Commands

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READ

The READ command is used to initiate a burst read access to an active row. The values

on the BA0 and BA1 inputs select the bank; the address provided selects the starting col-

umn location. The value on input A10 determines whether auto precharge is used. If au-

to precharge is selected, the row being accessed is precharged at the end of the READ

burst; if auto precharge is not selected, the row remains open for subsequent accesses.

Read data appears on the DQ subject to the logic level on the DQM inputs two clocks

earlier. If a given DQM signal was registered HIGH, the corresponding DQ will be High-

Z two clocks later; if the DQM signal was registered LOW, the DQ will provide valid data.

Figure 11: READ Command

CS#

WE#

CAS#

RAS#

CKE

CLK

Column address

A101

BA0, BA1

Don’t Care

HIGH

EN AP

DIS AP

Bank address

Address

Note: 1. EN AP = enable auto precharge, DIS AP = disable auto precharge.

64Mb: x4, x8, x16 SDRAM

Commands

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WRITE

The WRITE command is used to initiate a burst write access to an active row. The values

on the BA0 and BA1 inputs select the bank; the address provided selects the starting col-

umn location. The value on input A10 determines whether auto precharge is used. If au-

to precharge is selected, the row being accessed is precharged at the end of the write

burst; if auto precharge is not selected, the row remains open for subsequent accesses.

Input data appearing on the DQ is written to the memory array, subject to the DQM in-

put logic level appearing coincident with the data. If a given DQM signal is registered

LOW, the corresponding data is written to memory; if the DQM signal is registered

HIGH, the corresponding data inputs are ignored and a WRITE is not executed to that

byte/column location.

Figure 12: WRITE Command

DIS AP

EN AP

CS#

WE#

CAS#

RAS#

CKE

CLK

Column address

Don’t Care

HIGH

Bank address

Address

BA0, BA1

Valid address

A101

Note: 1. EN AP = enable auto precharge, DIS AP = disable auto precharge.

64Mb: x4, x8, x16 SDRAM

Commands

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PRECHARGE

The PRECHARGE command is used to deactivate the open row in a particular bank or

the open row in all banks. The bank(s) will be available for a subsequent row access a

specified time (tRP) after the PRECHARGE command is issued. Input A10 determines

whether one or all banks are to be precharged, and in the case where only one bank is

precharged, inputs BA0 and BA1 select the bank. Otherwise BA0 and BA1 are treated as

“Don’t Care.” After a bank has been precharged, it is in the idle state and must be acti-

vated prior to any READ or WRITE commands are issued to that bank.

Figure 13: PRECHARGE Command

CS#

WE#

CAS#

RAS#

CKE

CLK

A10

Don’t Care

HIGH

All banks

Bank selected

Address

BA0, BA1 Bank address

Valid address

BURST TERMINATE

The BURST TERMINATE command is used to truncate either fixed-length or continu-

ous page bursts. The most recently registered READ or WRITE command prior to the

BURST TERMINATE command is truncated.

64Mb: x4, x8, x16 SDRAM

Commands

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REFRESH

AUTO REFRESH

AUTO REFRESH is used during normal operation of the SDRAM and is analogous to

CAS#-BEFORE-RAS# (CBR) refresh in conventional DRAMs. This command is nonper-

sistent, so it must be issued each time a refresh is required. All active banks must be pre-

charged prior to issuing an AUTO REFRESH command. The AUTO REFRESH command

should not be issued until the minimum tRP has been met after the PRECHARGE com-

mand, as shown in Bank/Row Activation (page 46).

The addressing is generated by the internal refresh controller. This makes the address

bits a “Don’t Care” during an AUTO REFRESH command. Regardless of device width,

the 64Mb SDRAM requires 4096 AUTO REFRESH cycles every 64ms (commercial and

industrial) or 16ms (automotive). Providing a distributed AUTO REFRESH command

every 15.625μs (commercial and industrial) or 3.906μs (automotive) will meet the re-

fresh requirement and ensure that each row is refreshed. Alternatively, 4096 AUTO RE-

FRESH commands can be issued in a burst at the minimum cycle rate (tRFC), once ev-

ery 64ms (commercial and industrial) or 16ms (automotive).

SELF REFRESH

The SELF REFRESH command can be used to retain data in the SDRAM, even if the rest

of the system is powered-down. When in the self refresh mode, the SDRAM retains data

without external clocking.

The SELF REFRESH command is initiated like an AUTO REFRESH command except

CKE is disabled (LOW). After the SELF REFRESH command is registered, all the inputs

to the SDRAM become a “Don’t Care” with the exception of CKE, which must remain

LOW.

After self refresh mode is engaged, the SDRAM provides its own internal clocking, caus-

ing it to perform its own AUTO REFRESH cycles. The SDRAM must remain in self re-

fresh mode for a minimum period equal to tRAS and may remain in self refresh mode

for an indefinite period beyond that.

The procedure for exiting self refresh requires a sequence of commands. First, CLK

must be stable (stable clock is defined as a signal cycling within timing constraints

specified for the clock pin) prior to CKE going back HIGH. After CKE is HIGH, the

SDRAM must have NOP commands issued (a minimum of two clocks) for tXSR because

time is required for the completion of any internal refresh in progress.

Upon exiting the self refresh mode, AUTO REFRESH commands must be issued at the

specified intervals, as both SELF REFRESH and AUTO REFRESH utilize the row refresh

counter.

Self refresh is not supported on automotive temperature devices.

64Mb: x4, x8, x16 SDRAM

Commands

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Truth Tables

Table 15: Truth Table – Current State Bank n, Command to Bank n

Notes 1–6 apply to all parameters and conditions

Current State CS# RAS# CAS# WE# Command/Action Notes

Any H X X X COMMAND INHIBIT (NOP/continue previous operation)

L H H H NO OPERATION (NOP/continue previous operation)

Idle L L H H ACTIVE (select and activate row)

L L L H AUTO REFRESH 7

L L L L LOAD MODE REGISTER 7

L L H L PRECHARGE 8

Row active L H L H READ (select column and start READ burst) 9

L H L L WRITE (select column and start WRITE burst) 9

L L H L PRECHARGE (deactivate row in bank or banks) 10

Read

(auto precharge disabled)

L H L H READ (select column and start new READ burst) 9

L H L L WRITE (select column and start WRITE burst) 9

L L H L PRECHARGE (truncate READ burst, start PRECHARGE) 10

L H H L BURST TERMINATE 11

Write

(auto precharge disabled)

L H L H READ (select column and start READ burst) 9

L H L L WRITE (select column and start new WRITE burst) 9

L L H L PRECHARGE (truncate WRITE burst, start PRECHARGE) 10

L H H L BURST TERMINATE 11

Notes: 1. This table applies when CKEn-1 was HIGH and CKEn is HIGH (see Table 17 (page 38))

and after tXSR has been met (if the previous state was self refresh).

2. This table is bank-specific, except where noted (for example, the current state is for a

specific bank and the commands shown can be issued to that bank when in that state).

Exceptions are covered below.

3. Current state definitions:

Idle: The bank has been precharged, and tRP has been met.

Row active: A row in the bank has been activated, and tRCD has been met. No data

bursts/accesses and no register accesses are in progress.

Read: A READ burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

Write: A WRITE burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

4. The following states must not be interrupted by a command issued to the same bank.

COMMAND INHIBIT or NOP commands, or supported commands to the other bank

should be issued on any clock edge occurring during these states. Supported commands

to any other bank are determined by the bank’s current state and the conditions descri-

bed in this and the following table.

Precharging: Starts with registration of a PRECHARGE command and ends when tRP is

met. After tRP is met, the bank will be in the idle state.

Row activating: Starts with registration of an ACTIVE command and ends when tRCD is

met. After tRCD is met, the bank will be in the row active state.

64Mb: x4, x8, x16 SDRAM

Truth Tables

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Read with auto precharge enabled: Starts with registration of a READ command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

Write with auto precharge enabled: Starts with registration of a WRITE command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

5. The following states must not be interrupted by any executable command; COMMAND

INHIBIT or NOP commands must be applied on each positive clock edge during these

states.

Refreshing: Starts with registration of an AUTO REFRESH command and ends when

tRFC is met. After tRFC is met, the device will be in the all banks idle state.

Accessing mode register: Starts with registration of a LOAD MODE REGISTER com-

mand and ends when tMRD has been met. After tMRD is met, the device will be in the

all banks idle state.

Precharging all: Starts with registration of a PRECHARGE ALL command and ends

when tRP is met. After tRP is met, all banks will be in the idle state.

6. All states and sequences not shown are illegal or reserved.

7. Not bank specific; requires that all banks are idle.

8. Does not affect the state of the bank and acts as a NOP to that bank.

9. READs or WRITEs listed in the Command/Action column include READs or WRITEs with

auto precharge enabled and READs or WRITEs with auto precharge disabled.

10. May or may not be bank specific; if all banks need to be precharged, each must be in a

valid state for precharging.

11. Not bank-specific; BURST TERMINATE affects the most recent READ or WRITE burst, re-

gardless of bank.

64Mb: x4, x8, x16 SDRAM

Truth Tables

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Table 16: Truth Table – Current State Bank n, Command to Bank m

Notes 1–6 apply to all parameters and conditions

Current State CS# RAS# CAS# WE# Command/Action Notes

Any H X X X COMMAND INHIBIT (NOP/continue previous operation)

L H H H NO OPERATION (NOP/continue previous operation)

Idle X X X X Any command otherwise supported for bank m

Row activating, active, or

precharging

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start READ burst) 7

L H L L WRITE (select column and start WRITE burst) 7

L L H L PRECHARGE

Read

(auto precharge disabled)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start new READ burst) 7, 10

L H L L WRITE (select column and start WRITE burst) 7, 11

L L H L PRECHARGE 9

Write

(auto precharge disabled)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start READ burst) 7, 12

L H L L WRITE (select column and start new WRITE burst) 7, 13

L L H L PRECHARGE 9

Read

(with auto precharge)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start new READ burst) 7, 8, 14

L H L L WRITE (select column and start WRITE burst) 7, 8, 15

L L H L PRECHARGE 9

Write

(with auto precharge)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start READ burst) 7, 8, 16

L H L L WRITE (select column and start new WRITE burst) 7, 8, 17

L L H L PRECHARGE 9

Notes: 1. This table applies when CKEn-1 was HIGH and CKEn is HIGH (Table 17 (page 38)), and

after tXSR has been met (if the previous state was self refresh).

2. This table describes alternate bank operation, except where noted; for example, the cur-

rent state is for bank n and the commands shown can be issued to bank m, assuming

that bank m is in such a state that the given command is supported. Exceptions are cov-

ered below.

3. Current state definitions:

Idle: The bank has been precharged, and tRP has been met.

Row active: A row in the bank has been activated, and tRCD has been met. No data

bursts/accesses and no register accesses are in progress.

Read: A READ burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

Write: A WRITE burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

64Mb: x4, x8, x16 SDRAM

Truth Tables

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Read with auto precharge enabled: Starts with registration of a READ command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

Write with auto precharge enabled: Starts with registration of a WRITE command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

4. AUTO REFRESH, SELF REFRESH, and LOAD MODE REGISTER commands can only be is-

sued when all banks are idle.

5. A BURST TERMINATE command cannot be issued to another bank; it applies to the bank

represented by the current state only.

6. All states and sequences not shown are illegal or reserved.

7. READs or WRITEs to bank m listed in the Command/Action column include READs or

WRITEs with auto precharge enabled and READs or WRITEs with auto precharge disa-

bled.

8. Concurrent auto precharge: Bank n will initiate the auto precharge command when its

burst has been interrupted by bank m burst.

9. The burst in bank n continues as initiated.

10. For a READ without auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the READ on bank n, CAS latency (CL) later.

11. For a READ without auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the READ on bank n when registered. DQM

should be used one clock prior to the WRITE command to prevent bus contention.

12. For a WRITE without auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the WRITE on bank n when registered, with

the data-out appearing CL later. The last valid WRITE to bank n will be data-in regis-

tered one clock prior to the READ to bank m.

13. For a WRITE without auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the WRITE on bank n when registered. The

last valid WRITE to bank n will be data-in registered one clock prior to the READ to bank

14. For a READ with auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the READ on bank n, CL later. The PRE-

CHARGE to bank n will begin when the READ to bank m is registered.

15. For a READ with auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the READ on bank n when registered. DQM

should be used two clocks prior to the WRITE command to prevent bus contention. The

PRECHARGE to bank n will begin when the WRITE to bank m is registered.

16. For a WRITE with auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the WRITE on bank n when registered, with

the data-out appearing CL later. The PRECHARGE to bank n will begin after tWR is met,

where tWR begins when the READ to bank m is registered. The last valid WRITE bank n

will be data-in registered one clock prior to the READ to bank m.

17. For a WRITE with auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the WRITE on bank n when registered. The

PRECHARGE to bank n will begin after tWR is met, where tWR begins when the WRITE

to bank m is registered. The last valid WRITE to bank n will be data registered one clock

to the WRITE to bank m.

64Mb: x4, x8, x16 SDRAM

Truth Tables

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Table 17: Truth Table – CKE

Notes 1–4 apply to all parameters and conditions

Current State CKEn-1 CKEnCommandnActionnNotes

Power-down L L X Maintain power-down

Self refresh X Maintain self refresh

Clock suspend X Maintain clock suspend

Power-down L H COMMAND INHIBIT or NOP Exit power-down 5

Self refresh COMMAND INHIBIT or NOP Exit self refresh 6

Clock suspend X Exit clock suspend 7

All banks idle H L COMMAND INHIBIT or NOP Power-down entry

All banks idle AUTO REFRESH Self refresh entry

Reading or writing VALID Clock suspend entry

H H See Table 16 (page 36).

Notes: 1. CKEn is the logic state of CKE at clock edge n; CKEn-1 was the state of CKE at the previ-

ous clock edge.

2. Current state is the state of the SDRAM immediately prior to clock edge n.

3. COMMANDn is the command registered at clock edge n, and ACTIONn is a result of

COMMANDn.

4. All states and sequences not shown are illegal or reserved.

5. Exiting power-down at clock edge n will put the device in the all banks idle state in time

for clock edge n + 1 (provided that tCKS is met).

6. Exiting self refresh at clock edge n will put the device in the all banks idle state after

tXSR is met. COMMAND INHIBIT or NOP commands should be issued on any clock edges

occurring during the tXSR period. A minimum of two NOP commands must be provided

during the tXSR period.

7. After exiting clock suspend at clock edge n, the device will resume operation and recog-

nize the next command at clock edge n + 1.

64Mb: x4, x8, x16 SDRAM

Truth Tables

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Initialization

SDRAM must be powered up and initialized in a predefined manner. Operational proce-

dures other than those specified may result in undefined operation. After power is ap-

plied to VDD and VDDQ (simultaneously) and the clock is stable (stable clock is defined

as a signal cycling within timing constraints specified for the clock pin), the SDRAM re-

quires a 100μs delay prior to issuing any command other than a COMMAND INHIBIT or

NOP. Starting at some point during this 100μs period and continuing at least through

the end of this period, COMMAND INHIBIT or NOP commands must be applied.

After the 100μs delay has been satisfied with at least one COMMAND INHIBIT or NOP

command having been applied, a PRECHARGE command should be applied. All banks

must then be precharged, thereby placing the device in the all banks idle state.

Once in the idle state, at least two AUTO REFRESH cycles must be performed. After the

AUTO REFRESH cycles are complete, the SDRAM is ready for mode register program-

ming. Because the mode register will power up in an unknown state, it must be loaded

prior to applying any operational command. If desired, the two AUTO REFRESH com-

mands can be issued after the LMR command.

The recommended power-up sequence for SDRAM:

1. Simultaneously apply power to VDD and VDDQ.

2. Assert and hold CKE at a LVTTL logic LOW since all inputs and outputs are LVTTL-

compatible.

3. Provide stable CLOCK signal. Stable clock is defined as a signal cycling within tim-

ing constraints specified for the clock pin.

4. Wait at least 100μs prior to issuing any command other than a COMMAND INHIB-

IT or NOP.

5. Starting at some point during this 100μs period, bring CKE HIGH. Continuing at

least through the end of this period, 1 or more COMMAND INHIBIT or NOP com-

mands must be applied.

6. Perform a PRECHARGE ALL command.

7. Wait at least tRP time; during this time NOPs or DESELECT commands must be

given. All banks will complete their precharge, thereby placing the device in the all

banks idle state.

8. Issue an AUTO REFRESH command.

9. Wait at least tRFC time, during which only NOPs or COMMAND INHIBIT com-

mands are allowed.

10. Issue an AUTO REFRESH command.

11. Wait at least tRFC time, during which only NOPs or COMMAND INHIBIT com-

mands are allowed.

12. The SDRAM is now ready for mode register programming. Because the mode reg-

ister will power up in an unknown state, it should be loaded with desired bit values

prior to applying any operational command. Using the LMR command, program

the mode register. The mode register is programmed via the MODE REGISTER SET

command with BA1 = 0, BA0 = 0 and retains the stored information until it is pro-

grammed again or the device loses power. Not programming the mode register

upon initialization will result in default settings which may not be desired. Out-

puts are guaranteed High-Z after the LMR command is issued. Outputs should be

High-Z already before the LMR command is issued.

13. Wait at least tMRD time, during which only NOP or DESELECT commands are al-

lowed.

At this point the DRAM is ready for any valid command.

64Mb: x4, x8, x16 SDRAM

Initialization

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Note:

More than two AUTO REFRESH commands can be issued in the sequence. After steps 9

and 10 are complete, repeat them until the desired number of AUTO REFRESH + tRFC

loops is achieved.

Figure 14: Initialize and Load Mode Register

tCH

tCL

tCK

CKE

COMMAND

BA[1:0] BANK

tRFC tMRD

tRFC

AUTO REFRESH AUTO REFRESH Program Mode Register1,3,4

tCMH

tCMS

Precharge

all banks

(

)(

)

(

)(

)

(

)(

)

(

)(

)

tRP

(

)(

)

(

)(

)

tCKS

Power-up:

VDD and

CLK stable

T = 100µs

MIN

PRECHARGE AUTO

REFRESH

LOAD MODE

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

AUTO

REFRESH

ALL

BANKS

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

High-Z

tCKH

(

)(

)

(

)(

)

DQM/DQML,

DQMU

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

NOP2NOP2NOP2NOP2

(

)(

)

(

)(

)

A[9:0],

A[12:11] ROW

tAH5

tAS

tAH

tAS

CODE

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

A10 ROW

CODE

(

)(

)

(

)(

)

(

)(

)

(

)(

)

ALL BANKS

SINGLE BANK

(

)(

)

(

)(

)

(

)(

)

(

)(

)

DON’T CARE

UNDEFINED

T0 T1 Tn + 1 To + 1 Tp + 1 Tp + 2 Tp + 3

Notes: 1. The mode register may be loaded prior to the AUTO REFRESH cycles if desired.

2. If CS is HIGH at clock HIGH time, all commands applied are NOP.

3. JEDEC and PC100 specify three clocks.

4. Outputs are guaranteed High-Z after command is issued.

5. A12 should be a LOW at tP + 1.

64Mb: x4, x8, x16 SDRAM

Initialization

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Mode Register

The mode register defines the specific mode of operation, including burst length (BL),

burst type, CAS latency (CL), operating mode, and write burst mode. The mode register

is programmed via the LOAD MODE REGISTER command and retains the stored infor-

mation until it is programmed again or the device loses power.

Mode register bits M[2:0] specify the BL; M3 specifies the type of burst; M[6:4] specify

the CL; M7 and M8 specify the operating mode; M9 specifies the write burst mode; and

M10–Mn should be set to zero to ensure compatibility with future revisions. Mn + 1 and

Mn + 2 should be set to zero to select the mode register.

The mode registers must be loaded when all banks are idle, and the controller must wait

tMRD before initiating the subsequent operation. Violating either of these requirements

will result in unspecified operation.

64Mb: x4, x8, x16 SDRAM

Mode Register

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Figure 15: Mode Register Definition

M3 = 0

Reserved

Full Page

M3 = 1

Reserved

Operating Mode

Standard Operation

All other states reserved

–

Defined

–

Burst Type

Sequential

Interleaved

CAS Latency

Reserved

Burst Length

Burst LengthCAS Latency BT

A9 A7 A6 A5 A4 A3

A8 A2 A1 A0

Mode Register (Mx)

Address Bus

76543

821 0

M6-M0

M8 M7

Op Mode

A10

A11

Reserved WB

Write Burst Mode

Programmed Burst Length

Single Location Access

Program

BA1, BA0 = “0, 0”

to ensure compatibility

with future devices.

A12

12 9

64Mb: x4, x8, x16 SDRAM

Mode Register

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Burst Length

Read and write accesses to the device are burst oriented, and the burst length (BL) is

programmable. The burst length determines the maximum number of column loca-

tions that can be accessed for a given READ or WRITE command. Burst lengths of 1, 2,

4, 8, or continuous locations are available for both the sequential and the interleaved

burst types, and a continuous page burst is available for the sequential type. The con-

tinuous page burst is used in conjunction with the BURST TERMINATE command to

generate arbitrary burst lengths.

Reserved states should not be used, as unknown operation or incompatibility with fu-

ture versions may result.

When a READ or WRITE command is issued, a block of columns equal to the burst

length is effectively selected. All accesses for that burst take place within this block,

meaning that the burst wraps within the block when a boundary is reached. The block

is uniquely selected by A[8:1] when BL = 2, A[8:2] when BL = 4, and A[8:3] when BL = 8.

The remaining (least significant) address bit(s) is (are) used to select the starting loca-

tion within the block. Continuous page bursts wrap within the page when the boundary

is reached.

Burst Type

Accesses within a given burst can be programmed to be either sequential or interleaved;

this is referred to as the burst type and is selected via bit M3.

The ordering of accesses within a burst is determined by the burst length, the burst

type, and the starting column address.

64Mb: x4, x8, x16 SDRAM

Mode Register

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Table 18: Burst Definition Table

Burst Length Starting Column Address

Order of Accesses Within a Burst

Type = Sequential Type = Interleaved

2 A0

0 0-1 0-1

1 1-0 1-0

4 A1 A0

0 0 0-1-2-3 0-1-2-3

0 1 1-2-3-0 1-0-3-2

1 0 2-3-0-1 2-3-0-1

1 1 3-0-1-2 3-2-1-0

8 A2 A1 A0

0 0 0 0-1-2-3-4-5-6-7 0-1-2-3-4-5-6-7

0 0 1 1-2-3-4-5-6-7-0 1-0-3-2-5-4-7-6

0 1 0 2-3-4-5-6-7-0-1 2-3-0-1-6-7-4-5

0 1 1 3-4-5-6-7-0-1-2 3-2-1-0-7-6-5-4

1 0 0 4-5-6-7-0-1-2-3 4-5-6-7-0-1-2-3

1 0 1 5-6-7-0-1-2-3-4 5-4-7-6-1-0-3-2

1 1 0 6-7-0-1-2-3-4-5 6-7-4-5-2-3-0-1

1 1 1 7-0-1-2-3-4-5-6 7-6-5-4-3-2-1-0

Continuous

n = A0–An/9/8 (location 0–y) Cn, Cn + 1, Cn + 2, Cn + 3...Cn - 1,

Cn...

Not supported

Notes: 1. For full-page accesses: y = 2048 (x4); y = 1024 (x8); y = 512 (x16).

2. For BL = 2, A1–A9, A11 (x4); A1–A9 (x8); or A1–A8 (x16) select the block-of-two burst; A0

selects the starting column within the block.

3. For BL = 4, A2–A9, A11 (x4); A2–A9 (x8); or A2–A8 (x16) select the block-of-four burst;

A0–A1 select the starting column within the block.

4. For BL = 8, A3–A9, A11 (x4); A3–A9 (x8); or A3–A8 (x16) select the block-of-eight burst;

A0–A2 select the starting column within the block.

5. For a full-page burst, the full row is selected and A0–A9, A11 (x4); A0–A9 (x8); or A0–A8

(x16) select the starting column.

6. Whenever a boundary of the block is reached within a given sequence above, the fol-

lowing access wraps within the block.

7. For BL = 1, A0–A9, A11 (x4); A0–A9 (x8); or A0–A8 (x16) select the unique column to be

accessed, and mode register bit M3 is ignored.

64Mb: x4, x8, x16 SDRAM

Mode Register

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CAS Latency

The CAS latency (CL) is the delay, in clock cycles, between the registration of a READ

command and the availability of the output data. The latency can be set to two or three

clocks.

If a READ command is registered at clock edge n, and the latency is m clocks, the data

will be available by clock edge n + m. The DQ start driving as a result of the clock edge

one cycle earlier (n + m - 1), and provided that the relevant access times are met, the

data is valid by clock edge n + m. For example, assuming that the clock cycle time is

such that all relevant access times are met, if a READ command is registered at T0 and

the latency is programmed to two clocks, the DQ start driving after T1 and the data is

valid by T2.

Reserved states should not be used as unknown operation or incompatibility with fu-

ture versions may result.

Figure 16: CAS Latency

CLK

T2T1 T3T0

CL = 3

tLZ

DOUT

tOH

Command NOPREAD NOP

NOP

Don’t Care Undefined

CLK

T2T1 T3T0

CL = 2

tLZ

DOUT

tOH

Command NOPREAD

tAC

NOP

Operating Mode

The normal operating mode is selected by setting M7 and M8 to zero; the other combi-

nations of values for M7 and M8 are reserved for future use. Reserved states should not

be used because unknown operation or incompatibility with future versions may result.

Write Burst Mode

When M9 = 0, the burst length programmed via M[2:0] applies to both READ and

WRITE bursts; when M9 = 1, the programmed burst length applies to READ bursts, but

write accesses are single-location (nonburst) accesses.

64Mb: x4, x8, x16 SDRAM

Mode Register

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Bank/Row Activation

Before any READ or WRITE commands can be issued to a bank within the SDRAM, a

row in that bank must be opened. This is accomplished via the ACTIVE command,

which selects both the bank and the row to be activated.

After a row is opened with the ACTIVE command, a READ or WRITE command can be

issued to that row, subject to the tRCD specification. tRCD (MIN) should be divided by

the clock period and rounded up to the next whole number to determine the earliest

clock edge after the ACTIVE command on which a READ or WRITE command can be

entered. For example, a tRCD specification of 20ns with a 125 MHz clock (8ns period)

results in 2.5 clocks, rounded to 3. This is reflected in Figure 17 (page 46), which covers

any case where 2 < tRCD (MIN)/tCK ≤ 3. (The same procedure is used to convert other

specification limits from time units to clock cycles.)

A subsequent ACTIVE command to a different row in the same bank can only be issued

after the previous active row has been precharged. The minimum time interval between

successive ACTIVE commands to the same bank is defined by tRC.

A subsequent ACTIVE command to another bank can be issued while the first bank is

being accessed, which results in a reduction of total row-access overhead. The mini-

mum time interval between successive ACTIVE commands to different banks is defined

by tRRD.

Figure 17: Example: Meeting tRCD (MIN) When 2 < tRCD (MIN)/tCK < 3

CLK

T2T1 T3T0

Command NOPACTIVE READ or

WRITE

NOP

RCD(MIN)

tCK tCK tCK

Don’t Care

64Mb: x4, x8, x16 SDRAM

Bank/Row Activation

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READ Operation

READ bursts are initiated with a READ command, as shown in Figure 11 (page 30). The

starting column and bank addresses are provided with the READ command, and auto

precharge is either enabled or disabled for that burst access. If auto precharge is ena-

bled, the row being accessed is precharged at the completion of the burst. In the follow-

ing figures, auto precharge is disabled.

During READ bursts, the valid data-out element from the starting column address is

available following the CAS latency after the READ command. Each subsequent data-

out element will be valid by the next positive clock edge. Figure 19 (page 49) shows

general timing for each possible CAS latency setting.

Upon completion of a burst, assuming no other commands have been initiated, the DQ

signals will go to High-Z. A continuous page burst continues until terminated. At the

end of the page, it wraps to column 0 and continues.

Data from any READ burst can be truncated with a subsequent READ command, and

data from a fixed-length READ burst can be followed immediately by data from a READ

command. In either case, a continuous flow of data can be maintained. The first data

element from the new burst either follows the last element of a completed burst or the

last desired data element of a longer burst that is being truncated. The new READ com-

mand should be issued x cycles before the clock edge at which the last desired data ele-

ment is valid, where x = CL - 1. This is shown in Figure 19 (page 49) for CL2 and CL3.

SDRAM devices use a pipelined architecture and therefore do not require the 2n rule as-

sociated with a prefetch architecture. A READ command can be initiated on any clock

cycle following a READ command. Full-speed random read accesses can be performed

to the same bank, or each subsequent READ can be performed to a different bank.

64Mb: x4, x8, x16 SDRAM

READ Operation

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Figure 18: Consecutive READ Bursts

Don’t Care

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOP

Bank,

Col n

NOP

Bank,

Col b

DOUT

n + 1

DOUT

n + 2

DOUT

n + 3

DOUT

READ

X = 1 cycle

CL = 2

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOP

Bank,

Col n

NOP

Bank,

Col b

DOUT DOUT DOUT DOUT

READ NOP

CL = 3 Transitioning data

X = 2 cycles

Note: 1. Each READ command can be issued to any bank. DQM is LOW.

64Mb: x4, x8, x16 SDRAM

READ Operation

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Figure 19: Random READ Accesses

CLK

T2T1 T4T3 T6T5T0

Command

Address

Don’t Care

DOUT DOUT DOUT DOUT

CLK

T2T1 T4T3 T5T0

Command

Address

READ NOP

Bank,

Col n

READ READ READ NOP

Bank,

Col a

Bank,

Col x

Bank,

Col m

READ NOP

Bank,

Col n

Bank,

Col a

READ READ READ NOP NOP

Bank,

Col x

Bank,

Col m

CL = 2

CL = 3

DOUT DOUT DOUT DOUT

Transitioning data

Note: 1. Each READ command can be issued to any bank. DQM is LOW.

Data from any READ burst can be truncated with a subsequent WRITE command, and

data from a fixed-length READ burst can be followed immediately by data from a

WRITE command (subject to bus turnaround limitations). The WRITE burst can be ini-

tiated on the clock edge immediately following the last (or last desired) data element

from the READ burst, provided that I/O contention can be avoided. In a given system

design, there is a possibility that the device driving the input data will go Low-Z before

the DQ go High-Z. In this case, at least a single-cycle delay should occur between the

last read data and the WRITE command.

The DQM input is used to avoid I/O contention, as shown in Figure 20 (page 50) and

Figure 21 (page 51). The DQM signal must be asserted (HIGH) at least two clocks prior

to the WRITE command (DQM latency is two clocks for output buffers) to suppress da-

ta-out from the READ. After the WRITE command is registered, the DQ will go to High-Z

(or remain High-Z), regardless of the state of the DQM signal, provided the DQM was

active on the clock just prior to the WRITE command that truncated the READ com-

mand. If not, the second WRITE will be an invalid WRITE. For example, if DQM was

LOW during T4, then the WRITEs at T5 and T7 would be valid, and the WRITE at T6

would be invalid.

64Mb: x4, x8, x16 SDRAM

READ Operation

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The DQM signal must be de-asserted prior to the WRITE command (DQM latency is

zero clocks for input buffers) to ensure that the written data is not masked. Figure 20

(page 50) shows where, due to the clock cycle frequency, bus contention is avoided

without having to add a NOP cycle, while Figure 21 (page 51) shows the case where an

additional NOP cycle is required.

A fixed-length READ burst may be followed by or truncated with a PRECHARGE com-

mand to the same bank, provided that auto precharge was not activated. The PRE-

CHARGE command should be issued x cycles before the clock edge at which the last de-

sired data element is valid, where x = CL - 1. This is shown in Figure 22 (page 51) for

each possible CL; data element n + 3 is either the last of a burst of four or the last de-

sired data element of a longer burst. Following the PRECHARGE command, a subse-

quent command to the same bank cannot be issued until tRP is met. Note that part of

the row precharge time is hidden during the access of the last data element(s).

In the case of a fixed-length burst being executed to completion, a PRECHARGE com-

mand issued at the optimum time (as described above) provides the same operation

that would result from the same fixed-length burst with auto precharge. The disadvant-

age of the PRECHARGE command is that it requires that the command and address

buses be available at the appropriate time to issue the command. The advantage of the

PRECHARGE command is that it can be used to truncate fixed-length or continuous

page bursts.

Figure 20: READ-to-WRITE

READ NOP NOP WRITE

NOP

CLK

T2T1 T4T3T0

DQM

Command

Address

Bank,

Col b

Bank,

Col n

tHZ

tCK

Don’t Care

Transitioning data

DOUT DIN

Note: 1. CL = 3. The READ command can be issued to any bank, and the WRITE command can be

to any bank. If a burst of one is used, DQM is not required.

64Mb: x4, x8, x16 SDRAM

READ Operation

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Figure 21: READ-to-WRITE With Extra Clock Cycle

Don’t Care

READ NOP NOPNOP NOP

DQM

CLK

DQ DOUT

T2T1 T4T3T0

Command

Address Bank,

Col n

WRITE

DIN

Bank,

Col b

tDS

tHZ

Transitioning data

Note: 1. CL = 3. The READ command can be issued to any bank, and the WRITE command can be

to any bank.

Figure 22: READ-to-PRECHARGE

Don’t Care

CLK

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOPNOP PRECHARGE ACTIVE

tRP

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOPNOP

DOUT DOUT DOUT

PRECHARGE ACTIVE

tRP

X = 1 cycle

CL = 2

CL = 3

X = 2 cycles

Bank

Col

Bank

Row

Bank

(

or all)

Bank

Col

Bank

Row

Bank

(

or all)

Transitioning data

DOUT DOUT DOUT DOUT

Note: 1. DQM is LOW.

64Mb: x4, x8, x16 SDRAM

READ Operation

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Continuous-page READ bursts can be truncated with a BURST TERMINATE command

and fixed-length READ bursts can be truncated with a BURST TERMINATE command,

provided that auto precharge was not activated. The BURST TERMINATE command

should be issued x cycles before the clock edge at which the last desired data element is

valid, where x = CL - 1. This is shown in Figure 23 (page 52) for each possible CAS la-

tency; data element n + 3 is the last desired data element of a longer burst.

Figure 23: Terminating a READ Burst

CLK

T2T1 T4T3 T6T5T0

Command

Address

NOP NOP NOP NOPNOP BURST

TERMINATE NOP

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOPNOP

DOUT DOUT DOUT

BURST

TERMINATE NOP

X = 1 cycle

CL = 2

CL = 3

X = 2 cycles

Don’t CareTransitioning data

Bank,

Col n

READ

Bank,

Col n

DOUT DOUT DOUT DOUT

Note: 1. DQM is LOW.

64Mb: x4, x8, x16 SDRAM

READ Operation

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Figure 24: Alternating Bank Read Accesses

Don’t Care Undefined

Enable auto precharge

tCH

tCL

tCK

tAC

tLZ

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

tOH

DOUT

tAC

tOH

tAC

tOH

tAC

DOUT

Command

tCMH

tCMS

NOP NOPACTIVE NOP READ NOP ACTIVE

tOH

DOUT

tAC tAC

READ

Enable auto precharge

Row

ACTIVE

Row

Bank 0 Bank 0 Bank 3 Bank 3 Bank 0

CKE

tCKH

tCKS

Column m Column b1

T0 T1 T2 T4T3 T5 T6 T7 T8

tRP - bank 0

tRAS - bank 0

tRCD - bank 0 tRCD - bank 0

CL - bank 0

tRCD - bank 3 CL - bank 3

tRC - bank 0

tRRD

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4 and CL = 2.

64Mb: x4, x8, x16 SDRAM

READ Operation

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Figure 25: READ Continuous Page Burst

tCH

tCL tCK

tAC

tLZ

tRCD CAS latency

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAC

tOH

DOUT

Row

tHZ

tOH

DOUT

tAC

tOH

DOUT

tAC

tOH

DOUT

tAC

tOH

DOUT

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Full page completed

All locations within same row

Don’t Care

Undefined

Command

tCMH

tCMS

NOPNOP NOPACTIVE NOP READ NOP BURST TERMNOP NOP

(

)(

)

(

)(

)

NOP

(

)(

)

(

)(

)

tAH

tAS

Bank

(

)(

)

(

)(

)

Bank

tCKH

tCKS

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Column m

T0 T1 T2 T4T3 T5 T6 Tn + 1 Tn + 2 Tn + 3 Tn + 4

BA0, BA1

DQM

Address

Full-page burst does not self-terminate.

Can use BURST TERMINATE command.

Note: 1. For this example, CL = 2.

64Mb: x4, x8, x16 SDRAM

READ Operation

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Figure 26: READ – DQM Operation

tCH

tCL

tCK

tAC

tLZ

tRCD CL = 2

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank

Row

Bank

tHZ

tAC

tLZ

tOH

DOUT

tOH

DOUT

tHZ

Command

tCMH

tCMS

NOPNOPNOP NOPACTIVE NOP READ NOP NOP

Disable auto precharge

Enable auto precharge

Don’t Care

Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4 and CL = 2.

64Mb: x4, x8, x16 SDRAM

READ Operation

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WRITE Operation

WRITE bursts are initiated with a WRITE command, as shown in Figure 12 (page 31).

The starting column and bank addresses are provided with the WRITE command and

auto precharge is either enabled or disabled for that access. If auto precharge is ena-

bled, the row being accessed is precharged at the completion of the burst. For the ge-

neric WRITE commands used in the following figures, auto precharge is disabled.

During WRITE bursts, the first valid data-in element is registered coincident with the

WRITE command. Subsequent data elements are registered on each successive positive

clock edge. Upon completion of a fixed-length burst, assuming no other commands

have been initiated, the DQ will remain at High-Z and any additional input data will be

ignored (see Figure 27 (page 56)). A continuous page burst continues until terminated;

at the end of the page, it wraps to column 0 and continues.

Data for any WRITE burst can be truncated with a subsequent WRITE command, and

data for a fixed-length WRITE burst can be followed immediately by data for a WRITE

command. The new WRITE command can be issued on any clock following the previ-

ous WRITE command, and the data provided coincident with the new command ap-

plies to the new command (see Figure 28 (page 57)). Data n + 1 is either the last of a

burst of two or the last desired data element of a longer burst.

SDRAM devices use a pipelined architecture and therefore do not require the 2n rule as-

sociated with a prefetch architecture. A WRITE command can be initiated on any clock

cycle following a previous WRITE command. Full-speed random write accesses within a

page can be performed to the same bank, as shown in Figure 29 (page 58), or each

subsequent WRITE can be performed to a different bank.

Figure 27: WRITE Burst

CLK

DQ DIN

T2T1 T3T0

Command

Address

NOP NOP

Don’t Care

WRITE

DIN

NOP

Bank,

Col n

Transitioning data

Note: 1. BL = 2. DQM is LOW.

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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Figure 28: WRITE-to-WRITE

CLK

T2T1T0

Command

Address

NOPWRITE WRITE

Bank,

Col n

Bank,

Col b

DIN DIN DIN

Don’t Care

Transitioning data

Note: 1. DQM is LOW. Each WRITE command may be issued to any bank.

Data for any WRITE burst can be truncated with a subsequent READ command, and

data for a fixed-length WRITE burst can be followed immediately by a READ command.

After the READ command is registered, data input is ignored and WRITEs will not be

executed (see Figure 30 (page 58)). Data n + 1 is either the last of a burst of two or the

last desired data element of a longer burst.

Data for a fixed-length WRITE burst can be followed by or truncated with a PRE-

CHARGE command to the same bank, provided that auto precharge was not activated.

A continuous-page WRITE burst can be truncated with a PRECHARGE command to the

same bank. The PRECHARGE command should be issued tWR after the clock edge at

which the last desired input data element is registered. The auto precharge mode re-

quires a tWR of at least one clock with time to complete, regardless of frequency.

In addition, when truncating a WRITE burst at high clock frequencies (tCK < 15ns), the

DQM signal must be used to mask input data for the clock edge prior to and the clock

edge coincident with the PRECHARGE command (see Figure 31 (page 59)). Data n + 1

is either the last of a burst of two or the last desired data element of a longer burst. Fol-

lowing the PRECHARGE command, a subsequent command to the same bank cannot

be issued until tRP is met.

In the case of a fixed-length burst being executed to completion, a PRECHARGE com-

mand issued at the optimum time (as described above) provides the same operation

that would result from the same fixed-length burst with auto precharge. The disadvant-

age of the PRECHARGE command is that it requires that the command and address

buses be available at the appropriate time to issue the command. The advantage of the

PRECHARGE command is that it can be used to truncate fixed-length bursts or continu-

ous page bursts.

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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Figure 29: Random WRITE Cycles

Don’t Care

CLK

DQ DIN

T2T1 T3T0

Command

Address

WRITE

Bank,

Col n

DIN DIN DIN

WRITE WRITE WRITE

Bank,

Col a

Bank,

Col x

Bank,

Col m

Transitioning data

Note: 1. Each WRITE command can be issued to any bank. DQM is LOW.

Figure 30: WRITE-to-READ

Don’t Care

CLK

T2T1 T3T0

Command

Address

NOPWRITE

Bank,

Col n

DIN DIN DOUT

READ NOP NOP

Bank,

Col b

NOP

DOUT

T4 T5

Transitioning data

Note: 1. The WRITE command can be issued to any bank, and the READ command can be to any

bank. DQM is LOW. CL = 2 for illustration.

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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Figure 31: WRITE-to-PRECHARGE

Don’t Care

DQM

CLK

T2T1 T4T3T0

Command

Address Bank a,

Col n

NOPWRITE PRECHARGE NOPNOP

DIN DIN

ACTIVE

tRP

Bank

(a or all)

tWR

Bank a,

Row

DQM

Command

Address Bank a,

Col n

NOPWRITE PRECHARGE NOPNOP ACTIVE

tRP

Bank

(a or all)

tWR

Bank a,

Row

NOP

tWR @ tCK < 15ns

tWR @ tCK ≥ 15ns

DIN DIN

Transitioning data

Note: 1. In this example DQM could remain LOW if the WRITE burst is a fixed length of two.

Fixed-length WRITE bursts can be truncated with the BURST TERMINATE command.

When truncating a WRITE burst, the input data applied coincident with the BURST

TERMINATE command is ignored. The last data written (provided that DQM is LOW at

that time) will be the input data applied one clock previous to the BURST TERMINATE

command. This is shown in Figure 32 (page 60), where data n is the last desired data

element of a longer burst.

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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Figure 32: Terminating a WRITE Burst

Don’t Care

CLK

T2T1T0

Command

Address Bank,

Col n

WRITE BURST

TERMINATE

COMMAND

DIN

Address

Data

Transitioning data

Note: 1. DQM is LOW.

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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Figure 33: Alternating Bank Write Accesses

Don’t Care

Enable auto precharge

tCH

tCL

tCK

CLK

A10

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Command

tCMH

tCMS

NOP NOPACTIVE NOP WRITE NOPNOP ACTIVEWRITE

Enable auto precharge

Row

ACTIVE

Row

Bank 0 Bank 0 Bank 1 Bank 1 Bank 0

CKE

tCKH

tCKS

Column m Column b

T0 T1 T2 T4T3 T5 T6 T7 T8 T9

tRP - bank 0

tRAS - bank 0

tRCD - bank 0 tRCD - bank 0

tWR - bank 1

tWR - bank 0

tRCD - bank 1

tRC - bank 0

tRRD

BA0, BA1

DQM

Address

DIN

tDH

tDS

DIN DIN DIN

tDH

tDS tDH

tDS

DIN

tDH

tDS

DIN

tDH

tDS

DIN

tDH

tDS

DIN

tDH

tDS

Note: 1. For this example, BL = 4.

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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Figure 34: WRITE – Continuous Page Burst

tCH

tCL tCK

tRCD

CKE

CLK

A10

tCMS

tAH

tAS

tAH

tAS

Row

Full-page burst

does not self-terminate.

Use BURST TERMINATE

command to stop.1, 2

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Full page completed Don’t Care

Command

tCMH

tCMS

NOPNOP NOPACTIVE NOP WRITE BURST TERMNOP NOP

(

)(

)

(

)(

)

(

)(

)

(

)(

)

DIN

tDH

tDS

DIN DIN DIN

tDH

tDS tDH

tDS

DIN

tDH

tDS

tAH

tAS

Bank

(

)(

)

(

)(

)

Bank

tCMH

tCKH

tCKS

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

All locations within same row

Column

T0 T1 T2 T3 T4 T5 Tn + 1 Tn + 2 Tn + 3

BA0, BA1

DQM

Address

Notes: 1. tWR must be satisfied prior to issuing a PRECHARGE command.

2. Page left open; no tRP.

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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Figure 35: WRITE – DQM Operation

Don’t Care

tCH

tCL

tCK

tRCD

CKE

CLK

A10

tCMS

tAH

tAS

Row

Bank

Row

Bank

Enable auto precharge

DIN

tDH

tDS

DIN DIN

tCMH

Command NOPNOP NOP

ACTIVE NOP WRITE NOPNOP

tCMS tCMH

tDH

tDS

tDH

tDS

tAH

tAS

tAH

tAS

Disable auto precharge

tCKH

tCKS

Column m

T0 T1 T2 T3 T4 T5 T6 T7

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4.

Burst Read/Single Write

The burst read/single write mode is entered by programming the write burst mode bit

(M9) in the mode register to a 1. In this mode, all WRITE commands result in the access

of a single column location (burst of one), regardless of the programmed burst length.

READ commands access columns according to the programmed burst length and se-

quence, just as in the normal mode of operation (M9 = 0).

64Mb: x4, x8, x16 SDRAM

WRITE Operation

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PRECHARGE Operation

The PRECHARGE command (see Figure 13 (page 32)) is used to deactivate the open row

in a particular bank or the open row in all banks. The bank(s) will be available for a sub-

sequent row access some specified time (tRP) after the PRECHARGE command is is-

sued. Input A10 determines whether one or all banks are to be precharged, and in the

case where only one bank is to be precharged (A10 = LOW), inputs BA0 and BA1 select

the bank. When all banks are to be precharged (A10 = HIGH), inputs BA0 and BA1 are

treated as “Don’t Care.” After a bank has been precharged, it is in the idle state and

must be activated prior to any READ or WRITE commands being issued to that bank.

Auto Precharge

Auto precharge is a feature that performs the same individual-bank PRECHARGE func-

tion described previously, without requiring an explicit command. This is accomplished

by using A10 to enable auto precharge in conjunction with a specific READ or WRITE

command. A precharge of the bank/row that is addressed with the READ or WRITE

command is automatically performed upon completion of the READ or WRITE burst,

except in the continuous page burst mode where auto precharge does not apply. In the

specific case of write burst mode set to single location access with burst length set to

continuous, the burst length setting is the overriding setting and auto precharge does

not apply. Auto precharge is nonpersistent in that it is either enabled or disabled for

each individual READ or WRITE command.

Auto precharge ensures that the precharge is initiated at the earliest valid stage within a

burst. Another command cannot be issued to the same bank until the precharge time

(tRP) is completed. This is determined as if an explicit PRECHARGE command was is-

sued at the earliest possible time, as described for each burst type in the Burst Type

(page 43) section.

Micron SDRAM supports concurrent auto precharge; cases of concurrent auto pre-

charge for READs and WRITEs are defined below.

READ with auto precharge interrupted by a READ (with or without auto precharge)

A READ to bank m will interrupt a READ on bank n following the programmed CAS la-

tency. The precharge to bank n begins when the READ to bank m is registered (see Fig-

ure 36 (page 65)).

READ with auto precharge interrupted by a WRITE (with or without auto precharge)

A WRITE to bank m will interrupt a READ on bank n when registered. DQM should be

used two clocks prior to the WRITE command to prevent bus contention. The pre-

charge to bank n begins when the WRITE to bank m is registered (see Figure 37

(page 66)).

WRITE with auto precharge interrupted by a READ (with or without auto precharge)

A READ to bank m will interrupt a WRITE on bank n when registered, with the data-out

appearing CL later. The precharge to bank n will begin after tWR is met, where tWR be-

gins when the READ to bank m is registered. The last valid WRITE to bank n will be da-

ta-in registered one clock prior to the READ to bank m (see Figure 42 (page 71)).

WRITE with auto precharge interrupted by a WRITE (with or without auto precharge)

A WRITE to bank m will interrupt a WRITE on bank n when registered. The precharge to

bank n will begin after tWR is met, where tWR begins when the WRITE to bank m is reg-

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PRECHARGE Operation

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istered. The last valid data WRITE to bank n will be data registered one clock prior to a

WRITE to bank m (see Figure 43 (page 71)).

Figure 36: READ With Auto Precharge Interrupted by a READ

Don’t Care

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command READ - AP

Bank n NOP NOPNOPNOP

DOUT DOUT DOUT

NOP

Bank n

CL = 3 (bank m)

Bank m

Address

Idle

NOP

Bank n,

Col a

Bank m,

Col d

READ - AP

Bank m

Internal

states

Page active READ with burst of 4 Interrupt burst, precharge

Page active READ with burst of 4 Precharge

RP - bank n tRP - bank m

CL = 3 (bank n)

Note: 1. DQM is LOW.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 37: READ With Auto Precharge Interrupted by a WRITE

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command NOPNOPNOPNOP

DIN

DIN DIN DIN

NOP

Bank n

Bank m

Address

Idle

NOP

DQM1

Bank n,

Col a

Bank m,

Col d

WRITE - AP

Bank m

Internal

States

Page

active READ with burst of 4 Interrupt burst, precharge

Page active WRITE with burst of 4 Write-back

RP -

bank

tWR - bank m

CL = 3 (bank n)

READ - AP

Bank n

Don’t CareTransitioning data

Note: 1. DQM is HIGH at T2 to prevent DOUTa + 1 from contending with DINd at T4.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 38: READ With Auto Precharge

tCH

tCL

tCK

tAC

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

tOH

DOUT m

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank

Row

Bank

tHZ

tOH

DOUT

m + 3

tAC

tOH

tAC

tOH

tAC

DOUT

m + 2

DOUT

m + 1

Command

tCMH

tCMS

NOPNOPNOP NOPACTIVE NOP READ NOP ACTIVE

Enable auto precharge

Don’t Care Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4 and CL = 2.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 39: READ Without Auto Precharge

tCH

tCL

tCK

tAC

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank(s) Bank

Row

Bank

tHZ

tOH

DOUT

tAC

tOH

tAC

tOH

tAC

DOUT

Command

tCMH

tCMS

PRECHARGENOPNOP NOPACTIVE NOP READ NOP ACTIVE

Disable auto precharge Single bank

All banks

Don’t Care Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4, CL = 2, and the READ burst is followed by a manual PRE-

CHARGE.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 40: Single READ With Auto Precharge

tCH

tCL

tCK

tAC tOH

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank

Row

Bank

Command

tCMH

tCMS

NOPNOPNOP NOPACTIVE NOP READ ACTIVE

Enable auto precharge

Don’t Care Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 1 and CL = 2.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 41: Single READ Without Auto Precharge

All banks

tCH

tCL

tCK

tAC

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank(s) Bank

Row

Bank

tHZ

Command

tCMH

tCMS

NOPNOPNOP PRECHARGE

ACTIVE NOP READ ACTIVE NOP

Disable auto precharge Single bank

Don’t Care

Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 1, CL = 2, and the READ burst is followed by a manual PRE-

CHARGE.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 42: WRITE With Auto Precharge Interrupted by a READ

Don’t Care

CLK

T2T1 T4T3 T6T5T0

Command WRITE - AP

Bank n NOPNOPNOPNOP

DIN

NOP NOP

Bank n

Bank m

Address Bank n,

Col a

Bank m,

Col d

READ - AP

Bank m

Internal

States

Page active WRITE with burst of 4 Interrupt burst, write-back Precharge

Page active READ with burst of 4

tRP - bank m

DOUT DOUT

CL = 3 (bank m)

RP - bank n

WR - bank n

Note: 1. DQM is LOW.

Figure 43: WRITE With Auto Precharge Interrupted by a WRITE

Don’t Care

CLK

T2T1 T4T3 T6T5T0

Command WRITE - AP

Bank n NOPNOPNOPNOP

DIN

DIN DIN

DIN DIN DIN

NOP

Bank n

Bank m

Address

NOP

Bank n,

Col a

Bank m,

Col d

WRITE - AP

Bank m

Internal

States

Page active WRITE with burst of 4 Interrupt burst, write-back Precharge

Page active WRITE with burst of 4 Write-back

WR - bank n tRP - bank n

tWR - bank m

Note: 1. DQM is LOW.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 44: WRITE With Auto Precharge

Enable auto precharge

tCH

tCL

tCK

tRP

tRAS

tRCD

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

Row

Bank

Row

Bank

tWR

Don’t Care

DIN

tDH

tDS

DIN DIN DIN

Command

CMH

CMS

NOPNOP NOPACTIVE NOP WRITE NOPNOP NOP

Row

Bank

Row

tAH

tAS

tAH

tAS

tDH

tDS tDH

tDS

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8 T9

DQM

BA0, BA1

Address

ACTIVE

Note: 1. For this example, BL = 4.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 45: WRITE Without Auto Precharge

Disable auto precharge

All banks

tCH

tCL

tCK

tRP

tRAS

tRCD

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

Row

Bank Bank

Row

Bank

tWR

Don’t Care

DIN

tDH

tDS

DIN DIN DIN

Command

CMH

CMS

NOPNOP NOPACTIVE NOP WRITE PRECHARGENOP NOP

Row

Bank

Row

tAH

tAS

tAH

tAS

tDH

tDS tDH

tDS

Single bank

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8 T9

DQM

BA0, BA1

Address

ACTIVE

Note: 1. For this example, BL = 4 and the WRITE burst is followed by a manual PRECHARGE.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 46: Single WRITE With Auto Precharge

Enable auto precharge

tCH

tCL

tCK

tRP

tRAS

tRCD

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

Row

Bank

Row

Bank

tWR

Don’t Care

DIN

tDH

tDS

Command

CMH

CMS

NOPNOP NOPACTIVE NOP WRITE NOP NOP

Row

Bank

Row

tAH

tAS

tAH

tAS

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

DQM

BA0, BA1

Address

ACTIVE

Note: 1. For this example, BL = 1.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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Figure 47: Single WRITE Without Auto Precharge

tCH

tCL

tCK

tRP

tRAS

tRCD tWR

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank Bank

Row

Bank

Command

tCMH

tCMS

NOPNOPNOP PRECHARGEACTIVE NOP WRITE ACTIVE NOP

Disable auto precharge

Don’t Care

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

DIN

tDH

tDS

All banks

Single bank

Note: 1. For this example, BL = 1 and the WRITE burst is followed by a manual PRECHARGE.

64Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

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AUTO REFRESH Operation

The AUTO REFRESH command is used during normal operation of the device to refresh

the contents of the array. This command is nonpersistent, so it must be issued each

time a refresh is required. All active banks must be precharged prior to issuing an AUTO

REFRESH command. The AUTO REFRESH command should not be issued until the

minimum tRP is met following the PRECHARGE command. Addressing is generated by

the internal refresh controller. This makes the address bits “Don’t Care” during an AU-

TO REFRESH command.

After the AUTO REFRESH command is initiated, it must not be interrupted by any exe-

cutable command until tRFC has been met. During tRFC time, COMMAND INHIBIT or

NOP commands must be issued on each positive edge of the clock. The SDRAM re-

quires that every row be refreshed each tREF period. Providing a distributed AUTO RE-

FRESH command—calculated by dividing the refresh period (tREF) by the number of

rows to be refreshed—meets the timing requirement and ensures that each row is re-

freshed. Alternatively, to satisfy the refresh requirement a burst refresh can be employed

after every tREF period by issuing consecutive AUTO REFRESH commands for the num-

ber of rows to be refreshed at the minimum cycle rate (tRFC).

64Mb: x4, x8, x16 SDRAM

AUTO REFRESH Operation

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Figure 48: Auto Refresh Mode

All banks

Don’t Care

tCH

tCL

tCK

CKE

CLK

tRFC

(

)(

)

(

)(

)

tRP

(

)(

)

(

)(

)

Command

tCMH

tCMS

NOPNOP

(

)(

)

(

)(

)

Bank

ACTIVE

AUTO

REFRESH

(

)(

)

(

)(

)

NOPNOPPRECHARGE

Precharge all

active banks

AUTO

REFRESH

tRFC

High-Z

Bank(s)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

tAH

tAS

tCKH

tCKS

NOP

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Row

(

)(

)

(

)(

)

Single bank

A10

Row

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

T0 T1 T2 Tn + 1 To + 1

BA0, BA1

Address

DQM

(

)(

)

(

)(

)

Note: 1. Back-to-back AUTO REFRESH commands are not required.

64Mb: x4, x8, x16 SDRAM

AUTO REFRESH Operation

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SELF REFRESH Operation

The self refresh mode can be used to retain data in the device, even when the rest of the

system is powered down. When in self refresh mode, the device retains data without ex-

ternal clocking. The SELF REFRESH command is initiated like an AUTO REFRESH com-

mand, except CKE is disabled (LOW). After the SELF REFRESH command is registered,

all the inputs to the device become “Don’t Care” with the exception of CKE, which must

remain LOW.

After self refresh mode is engaged, the device provides its own internal clocking, ena-

bling it to perform its own AUTO REFRESH cycles. The device must remain in self re-

fresh mode for a minimum period equal to tRAS and remains in self refresh mode for an

indefinite period beyond that.

The procedure for exiting self refresh requires a sequence of commands. First, CLK

must be stable prior to CKE going back HIGH. (Stable clock is defined as a signal cycling

within timing constraints specified for the clock ball.) After CKE is HIGH, the device

must have NOP commands issued for a minimum of two clocks for tXSR because time is

required for the completion of any internal refresh in progress.

Upon exiting the self refresh mode, AUTO REFRESH commands must be issued accord-

ing to the distributed refresh rate (tREF/refresh row count) as both SELF REFRESH and

AUTO REFRESH utilize the row refresh counter.

64Mb: x4, x8, x16 SDRAM

SELF REFRESH Operation

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Figure 49: Self Refresh Mode

All banks

tCH

tCL

tRP

CKE

CLK

Enter self refresh mode

Precharge all

active banks

tXSR

CLK stable prior to exiting

self refresh mode

Exit self refresh mode

(Restart refresh time base)

(

)(

)

(

)(

)

Don’t Care

Command

tCMH

tCMS

AUTO

REFRESH

PRECHARGE NOP NOP

Bank(s)

High-Z

tCKS

tAH

tAS

AUTO

REFRESH

tCKH

tCKS

A10

T0 T1 T2 Tn + 1 To + 1 To + 2

BA0, BA1

DQM

Address

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Single bank

Note: 1. Each AUTO REFRESH command performs a REFRESH cycle. Back-to-back commands are

not required.

64Mb: x4, x8, x16 SDRAM

SELF REFRESH Operation

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Power-Down

Power-down occurs if CKE is registered LOW coincident with a NOP or COMMAND IN-

HIBIT when no accesses are in progress. If power-down occurs when all banks are idle,

this mode is referred to as precharge power-down; if power-down occurs when there is a

row active in any bank, this mode is referred to as active power-down. Entering power-

down deactivates the input and output buffers, excluding CKE, for maximum power

savings while in standby. The device cannot remain in the power-down state longer

than the refresh period (64ms) because no REFRESH operations are performed in this

mode.

The power-down state is exited by registering a NOP or COMMAND INHIBIT with CKE

HIGH at the desired clock edge (meeting tCKS).

Figure 50: Power-Down Mode

All banks

tCH

tCL

tCK

Two clock cycles

CKE

CLK

All banks idle, enter

power-down mode

Precharge all

active banks

Input buffers gated off

while in power-down mode

Exit power-down mode

(

)(

)

Don’t Care

tCKS tCKS

Command

tCMH

tCMS

PRECHARGE NOP NOP ACTIVENOP

(

)(

)

(

)(

)

All banks idle

BA0, BA1 Bank

Bank(s)

(

)(

)

(

)(

)

High-Z

tAH

tAS

tCKH

tCKS

DQM

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Address Row

(

)(

)

(

)(

)

Single bank

A10 Row

(

)(

)

(

)(

)

T0 T1 T2 Tn + 1 Tn + 2

(

)(

)

Note: 1. Violating refresh requirements during power-down may result in a loss of data.

64Mb: x4, x8, x16 SDRAM

Power-Down

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Clock Suspend

The clock suspend mode occurs when a column access/burst is in progress and CKE is

registered LOW. In the clock suspend mode, the internal clock is deactivated, freezing

the synchronous logic.

For each positive clock edge on which CKE is sampled LOW, the next internal positive

clock edge is suspended. Any command or data present on the input balls when an in-

ternal clock edge is suspended will be ignored; any data present on the DQ balls re-

mains driven; and burst counters are not incremented, as long as the clock is suspen-

ded.

Exit clock suspend mode by registering CKE HIGH; the internal clock and related opera-

tion will resume on the subsequent positive clock edge.

Figure 51: Clock Suspend During WRITE Burst

Don’t Care

DIN

Command

Address

WRITE

Bank,

Col n

DIN

NOPNOP

CLK

T2T1 T4T3 T5T0

CKE

Internal

clock

NOP

DIN DIN

Note: 1. For this example, BL = 4 or greater, and DQM is LOW.

64Mb: x4, x8, x16 SDRAM

Clock Suspend

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Figure 52: Clock Suspend During READ Burst

Don’t Care

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP

Bank,

Col n

NOP

DOUT DOUT DOUT

CKE

Internal

clock

NOP

Note: 1. For this example, CL = 2, BL = 4 or greater, and DQM is LOW.

64Mb: x4, x8, x16 SDRAM

Clock Suspend

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Figure 53: Clock Suspend Mode

tCH

tCL

tCK

tAC

tLZ

DQM

CLK

A10

tOH

DOUT

tAH

tAS

tAH

tAS

tAH

tAS

Bank

tDH

DIN

tAC

tHZ

DOUT

Command

tCMH

tCMS

NOPNOP NOP NOPNOPREAD WRITE

Don’t Care Undefined

CKE

tCKS tCKH

Bank

Column m

tDS

DIN

NOP

tCKH

tCKS

tCMH

tCMS

Column e

T0 T1 T2 T3 T4 T5 T6 T7 T8 T9

BA0, BA1

Address

Note: 1. For this example, BL = 2, CL = 3, and auto precharge is disabled.

8000 S. Federal Way, P.O. Box 6, Boise, ID 83707-0006, Tel: 208-368-3900

www.micron.com/productsupport Customer Comment Line: 800-932-4992

Micron and the Micron logo are trademarks of Micron Technology, Inc.

All other trademarks are the property of their respective owners.

This data sheet contains minimum and maximum limits specified over the power supply and temperature range set forth herein.

Although considered final, these specifications are subject to change, as further product development and data characterization some-

times occur.

64Mb: x4, x8, x16 SDRAM

Clock Suspend

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64mb_x4x8x16_sdram.pdf - Rev. T 03/13 EN 83 Micron Technology, Inc. reserves the right to change products or specifications without notice.