AS4SD16M16DGC-75/IT - Micross Components, Inc.

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

FEATURES

• Full Military temp (-55°C to 125°C) processing available

• Copper lead frame option for enhanced reliability

• Conﬁ guration: 16 Meg x 16 (4 Meg x 16 x 4 banks)

• 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 Mode (IT & ET)

• 64ms, 8,192-cycle refresh (IT)

• 24ms 8,192 cycle recfresh (XT)

• WRITE Recovery (tWR = “2 CLK”)

• LVTTL- compatible inputs and outputs

• Single +3.3V ±0.3V power supply

OPTIONS MARKING

• Plastic Package – 54-pin TSOPII (400 mil)

- Alloy 42 lead frame- OCPL* DG No. 901

- Copper lead frame DGC

(Pb/Sn ﬁ nish or RoHS available)

• Timing (Cycle Time)

7.5ns @ CL = 3 (PC133) or -75

7.5ns @ CL = 2 (PC100)

• Operating Temperature Ranges

-Industrial Temp (-40°C to 85° C) IT

-Enhanced Temp (-40°C to +105°C) ET

-Military Temp (-55°C to 125°C) XT

*Off-center parting line

**CL = CAS (READ) latency

PIN ASSIGNMENT

(Top View)

54-Pin TSOP

Note: “\” indicates an active low.

256 MB: 16 Meg x 16 SDRAM

Synchronous DRAM Memory

For more products and information

please visit our web site at

www.micross.com

KEY TIMING PARAMETERS

SPEED CLOCK SETUP HOLD

GRADE FREQUENCY CL = 2** CL = 3** TIME TIME

-75 133 MHz – 5.4ns 1.5ns 0.8ns

-75 100 MHz 6ns – 1.5ns 0.8ns

ACCESS TIME

Configuration 4 Meg x 16 x 4 banks

Refresh Count 8K

Row Addressing 8K (A0-A12)

Bank Addressing 4 (BA0, BA1)

Column Addressing 512 (A0-A8)

16 Meg x 16

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

GENERAL DESCRIPTION

The 256MB SDRAM is a high-speed CMOS, dynamic

random-access memory containing 268,435,456 bits. It is

internally conﬁ gured as a quad-bank DRAM with a synchro-

nous interface (all signals are registered on the positive edge

of the clock signal, CLK). Each of the 67,108,864-bit banks

is organized as 8,192 rows by 512 columns by 16 bits.

Read and write accesses to the SDRAM are burst ori-

ented; accesses start at a selected location and continue for a

programmed number of locations in a programmed sequence.

Accesses begin with the registration of an ACTIVE command,

which is then 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, BA1

select the bank; A0-A12 select the row). The address bits regis-

tered 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 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 256MB SDRAM uses an internal pipelined archi-

tecture to achieve high-speed operation. This architecture is

compatible with the 2n rule of prefetch architectures, but it also

allows the column address to be changed on every clock cycle

to achieve a high-speed, fully random operation. Precharging

one bank while accessing one of the other three banks will

hide the precharge cycles and provide seamless, high-speed,

random-access operation.

The 256Mb 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 outputs are

LVTTL-compatible.

SDRAMs offer substantial advances in DRAM operating

performance, including the ability to synchronously burst data at

a high data rate with automatic column-address generation, the

ability to interleave between internal banks to hide precharge

time and the capability to randomly change column addresses

on each clock cycle during a burst access.

FUNCTIONAL BLOCK DIAGRAM

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

ENHANCING RELIABILITY WITH COPPER LEAD FRAMES1

ADVANTAGES & BENEFITS

Superior thermal conductivity improvement: 170 W/m*K •

vs. 14 W/m*K (a 12X difference).

θ ja and θ jc characteristics provide up to 3.8X advantage •

of heat dissipation capability versus parts with alloy 42

lead frames.

Heat dissipated from the die faster makes it run cooler •

leading to longer life.

Solder joint reliability vastly improved.•

- CTE of Copper (17 ppm/ oC), matches the CTE of Typical

FR4 PWBs (15-17 ppm/ oC)

- CTE of Alloy 42 (5 ppm/ oC), mismatch to CTE of FR4

PWBs (15-17 ppm/ oC)

RoHS Version (NiPdAu plating)•

- Most preferred for elimination of risk for whisker growth.

The use of copper lead frames inherently allow for better solder joint reliability, tin whisker prevention and

better thermal dissipation. These are three big factors in overall system reliability over time.

Better Solder Joint Reliability

Many systems are expected to operate reliably over broad temperature variations spanning the industrial

(-400C to +850C) and military (-550C to +1250C) temperature ranges. System problems can be caused

by the mismatch of thermal coefﬁ cients of all system components. Better solder joint reliability is obtained

since the copper lead frame is more ﬂ exible, and the CTE of the copper lead frame is better matched with

that of typical FR4 PWBs, than that of Alloy 42. Repeated thermal cycles over a period of time can take a

toll on solder joints, causing cracks and intermittent connections where expansion and contraction of the

lead frame is at a different rate than the FR4 PWB that it is attached to.

Whisker Prevention

The RoHS version of this copper lead frame, with its’ NiPdAu (Nickel-Palladium-Gold) plating, eliminates

the risk of tin whiskers. Microscopic whiskers can grow on a parts’ pins than have tin content in the plat-

ing. Traditionally Alloy 42 lead frames have a Sn or PbSn plating. This plating containing tin, along with

certain environmental conditions can cause these whiskers to grow. Their growth may extend to form a

bridge with another pin on the device, or the whisker may break off and cause a short circuit or even an

explosive power surge on the board. The organization, iNEMI (International Electronics Manufacturing

Initiative) lists the NiPdAu lead plating as the most preferred for elimination of risk for whiskers.

Better Thermal Dissipation

Because copper has a 10X to 12X improvement in thermal conductivity vs. Alloy 42, and since θ ja and θ jc

characteristics of copper provide up to 3.8X advantage over Alloy 42, more efﬁ cient thermal dissipation is

the result. This translates to better heat dissipated away from the chip through the lead frame and PWB,

thus extending the useful life of the die by reducing die junction temperature. Therefore less heat stress

remains in the device, which is a leading cause of non-mechanical failure in a long life application.

1Source: ISSI white paper; “Enhancing Long-Term Reliability with Copper Lead Frames.”

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

ENHANCING RELIABILITY WITH COPPER LEAD FRAMES

Thermal Impedance Data - Cu LF vs. Alloy 42, 54 Lead TSOP II

With copper lead frames, the die stays cooler, and results in greater component

reliability and longer life. This equates to improved system reliability and lower

service costs and greater system quality conﬁ dence.

CuLF CuLF Alloy42LF Alloy42LF Alloy42LF

ȺͲja ȺͲjc ȺͲja ȺͲja ȺͲjc ȺͲja ȺͲjc

oC/Watt oC/Watt oC/Watt oC/Watt oC/Watt CuLFAdvantage CuLFAdvantage

2ͲLayer 4ͲLayer

64M 62 9 99.1 70.5 13.7 1.6X 1.5X

128M 53 7.8 86.2 58.9 11.3 1.6X 1.4X

256M 32.3 2.7 81 44 10.3 2.5X 3.8X

512M 25.2 2.8 62.6 39.2 6.7 2.5X 2.4X

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

PIN NUMBER SYMBOL TYPE DESCRIPTION

38 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.

37 CKE Input

Clock Enable: CKE activates (HIGH) and deactivates (LOW) the

CLK signal. Deactivating the clock provides PRECHARGE

POWER-DOWN and SLEF REFRESH operation (all banks idle),

ACTIVE POWER-DOWN (row active in any bank) or CLOCK

SUSPEND operation (burst/access in progress). 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, including CLK, are

disabled durin

power-down and self refresh modes, providin

low

standby power. CKE may be tied HIGH.

19 CS\ Input

Chip Select: CS\ enables (registered LOW) and disables

(registered HIGH) the command decoder. All commands are

masked when CS\ is registered HIGH. CS\ provides for external

bank selection on systems with multiple banks. CS\ in considered

part of the command code.

16, 17, 18 WE\, CAS\,

RAS\ Input Command Inputs: WE\, CAS\ and RAS\ (along with CS\) define

the command being entered.

15, 39 DQML, DQMU Input

Input/Output Mask: DQM is an input mask signal for write

accesses and an output enable signal for read accesses. Input

data is masked when DWM is sampled HIGH during a WRITE

cycle. The outptu buffers are placed in a High-Z state (two-clock

latency) when DQM is sampled HIGH during a READ cycle.

DQML corresponds to DQ0-DQ7 and DQMH corresponds to

DQ8-DQ15. DQML and DQMH are considered same state when

referenced as DQM.

20, 21 BA0, BA1 Input

Bank Address Inputs: BA0 and BA1 define to which bank the

ACTIVE, READ, WRITE, or PRECHARGE command is being

applied.

23-26, 29-34, 22, 35, 36 A0 - A12 Input

Address Inputs: A0-A12 are sampled during the ACTIVE

command (row address A0-A12) and READ/WRITE command

(column-address A0-A8; 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 if all banks are to be prechaged (A10 [HIGH]) or bank

selected by (A10 [LOW]). The address inputs also provide the

op-code during LOAD MODE REGISTER COMMAND.

2, 4, 5, 7, 8, 10, 11, 13, 42,

44, 45, 47, 48, 50, 51, 53 DQ0 - DQ15 I/O Data Input/Output: Data bus

40 NC --- No Connect: This pin should be left unconnected.

3, 9, 43, 49 VDDQ Supply DQ Power: Isolated DQ power to the die for improved noise

immunity.

6, 12, 46, 52 VSSQ Supply DQ Ground: Isolated DQ ground to the die for imporved noise

immunity.

1, 14, 27 VDD Supply Power Supply: +3.3V ±0.3V

28, 41, 54 VSS Supply Ground

PIN DESCRIPTIONS

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

FUNCTIONAL DESCRIPTION

In general, the 256MB SDRAMs are quad-bank DRAMs

that operate at 3.3V and include a synchronous interface (all

signals are registered on the positive edge of the clock signal,

CLK). Each of the 67,108,864-bit banks is organized as 8,192

rows by 512 columns by 16 bits.

Read and write accesses to the SDRAM are burst ori-

ented; accesses start at a selected location and continue for a

programmed number of locations in a programmed sequence.

Accesses begin with the registration of an ACTIVE command,

which is then 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, A0 - A12 select the row). The address

bits (A0 - A8) registered coincident with the READ or WRITE

command are used to select the starting column location for the

burst access.

Prior to normal operation, the SDRAM must be initialized.

The following sections provide detailed information covering

device initialization, register deﬁ nition, command descriptions

and device operation.

Initialization

SDRAMs must be powered up and initialized in a pre-

deﬁ ned manner. Operational procedures other than those

speciﬁ ed may result in undeﬁ ned operation. Once power is

applied to VDD and VDDQ (simultaneously) and the clock is

stable (stable clock is deﬁ ned as a signal cycling within timing

constraints speciﬁ ed for the clock pin), the SDRAM requires a

100μs delay prior to issuing any command other than a COM-

MAND 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 should

be applied.

Once the 100μs delay has been satisﬁ ed 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, two AUTO REFRESH cycles must

be preformed. After the AUTO REFRESH cycles are complete,

the SDRAM is ready for mode register programming. Because

the mode register will power up in an unknown state, it should

be loaded prior to applying any operational command.

MODE REGISTER

The mode register is used to deﬁ ne the speciﬁ c mode

of operation of the SDRAM. This deﬁ nition includes the

selection of a burst length, a burst type, a CAS latency, an

operating mode and a write burst mode, as shown in Figure

1. The mode register is programmed via the LOAD MODE

until it is programmed again or the device loses power.

Mode register bits M0 - M2 specify the burst length, M3

speciﬁ es the type of burst (sequential or interleaved), M4 - M6

specify the CAS latency, M7 and M8 specify the operating

mode, M9 speciﬁ es the write burst mode, and M10 and M11 are

reserved for future use. Address A12 (M12) is undeﬁ ned but

should be driven LOW during loading of the mode register.

The mode register must be loaded when all banks are idle,

and the controller must wait the speciﬁ ed time before initiating

the subsequent operation. Violating either of these requirements

will result in unspeciﬁ ed operation.

Burst Length

Read and write accesses to the SDRAM are burst oriented,

with the burst length being programmable, as shown in Figure 1.

The burst length determines the maximum number of column

locations that can be accessed for a given READ or WRITE

command. Burst lengths of 1, 2, 4, or 8 locations are available

for both the sequential and the interleaved burst types, and a full-

page burst is available for the sequential types. The full-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 future 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, mean-

ing that the burst will wrap within the block if a boundary is

reached. The clock is uniquely selected by A1-A8 when the

burst length is set to two; by A2-A8 when the burst length is

set to four, and by A3-A8 when the burst length is set to eight.

The remaining (least signiﬁ cant) address bit(s) is (are) used to

select the starting location within the block. Full-page bursts

wrap within the page if the boundary is reached.

Burst Type

Accesses within a given burst may 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,

shown in table 1.

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

FIGURE 1: Mode Register Deﬁ nition TABLE 1: Burst Deﬁ nition

TYPE = SEQUENTIAL TYPE = INTERLEAVED

0 0-1 0-1

1 1-0 1-0

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

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

Full

(y)

n=A0-A8

(location 0-y)

Cn, Cn+1, Cn+2, Cn+3,

Cn+4…

…Cn-1,

Cn…

Not Supported

BURST

LENGTH

STARTING

COLUMN

ORDER OF ACCESSES WITHIN A BURST

NOTES:

1. For full-page access: y=512

2. For a burst length of two, A1-A8 select the block-of-two burst;

A0 selects the starting column within the block.

3. For a burst length of four, A2-A8 select the block-of-four burst;

A0-A1 selects the starting column within the block.

4. For a burst length of eight, A3-A8 select the block-of-eight burst; A0-A2

selects the starting column within the block.

5. For a full-page burst, the full row is selected and A0-A8 select the starting

column.

6. Whenever a boundary of the block is reached within a given sequence

above, the following access wraps within the block.

7. For a burst length of one, A0-A8 select the unique column to be accessed,

and mode register bit M3 is ignored.

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

CAS Latency

The CAS latency is the delay, in clock cycles, between

the registration of a READ command and the availability of

the ﬁ rst piece of 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 DQs will 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 will be 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 DQs will start driving after T1 and the data will be valid by

T2, as shown in Figure 2. Table 2 below indicates the operating

frequencies at which each CAS latency setting can be used.

Reserved states should not be used as unknown operation

or incompatibility with future versions may result.

Operating Mode

The normal operating mode is selected by setting M7 and

M8 to zero; the other combinations of values for M7 and M8

are reserved for future use and/or test modes. The programmed

burst length applies to both READ and WRITE bursts.

Test modes are 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 M0-M2

applies to both READ and WRITE bursts; when M9=1, the

programmed burst length applies to READ bursts, but write

accesses are single-location (non-burst) accesses.

FIGURE 2: CAS Latency TABLE 2: CAS Latency

CAS

LATENCY = 2

CAS

LATENCY = 3

-75 <100 <133

SPEED

ALLOWABLE OPERATING

FREQUENCY

(

MHz

)

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

COMMANDS

Truth Table 1 provides a quick reference of available

commands. This is followed by a written description of each

command. Three additional Truth Tables appear following the

Operation section; these tables provide current state/next state

information.

COMMAND INHIBIT

The COMMAND INHIBIT function prevents new

commands from being executed by the SDRAM, regardless of

whether the CLK signal is enabled. The SDRAM is effectively

deselected. Operations already in progress are not affected.

NO OPERATION (NOP)

The NO OPERATION (NOP) command is used to per-

form a NOP to an SDRAM which is selected (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

The mode register is loaded via inputs A0-A11 (A12 should

be driven LOW). See mode register heading in the Register

Deﬁ nition section. The LOAD MODE REGISTER command

can only be issued when all banks are idle, and a subsequent

executable command cannot be issued until tMRD is met.

TRUTH TABLE 1: COMMANDS AND DQM OPERATION1

FUNCTION CS\ RAS\ CAS\ WE\ DQM ADDR DQs NOTES

COMMAND INHIBIT (NOP) HXXXXXX

NO OPERATION (NOP) LHHHXXX

ACTIVE (Select bank and activate row) L L H H X Bank/Row X 3

READ (Select bank and column, and start READ burst) LH L H

L/H8Bank/Col X 4

WRITE (Select bank and column, and start WRITE burst) LH L L

L/H8Bank/Col Valid 4

BURST TERMINATE L H H L X X Active

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 2

Write Enable/Output Enable - - - - L - Active 8

Write Inhibit/Output High-Z - - - - H - High-Z 8

NOTE:

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

2. A0-A11 deﬁ ne the op-code written to the mode register, and A12 should be driven LOW.

3. A0-A12 provide row address, and BA0, BA1 determine which bank is made active.

4. A0-A8 provide column address; A10 HIGH enables the auto precharge feature (nonpersistent), while A10 LOW disables the auto precharge feature; BA0,

BA1 determine which bank is being read from or written to.

5. A10 LOW: BA0, BA1 determine the bank being precharged. A10 HIGH: All banks precharged 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” except for CKE.

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

ACTIVE

The ACTIVE command is used to open (or 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

on inputs A0-A12 selects the row. The row remains active (or

open) for accesses until a PRECHARGE command is issued to

that bank. A PRECHARGE command must be issued before

opening a different row in the same bank.

READ

The READ command is used to initiate a burst read access

to an active row. The value on the BA0, BA1 inputs selects

the bank, and the address provided on inputs A0-A8 selects the

starting column location. The value on input A10 determines

whether or not auto precharge is used. If auto precharge is

selected, the row being accessed will be precharged at the end

of the READ burst; if auto precharge is not selected, the row

will remain open for subsequent accesses. Read data appears

on the DQs subject to the logic level on the DQM inputs two

clocks earlier. If a given DQM signal was registered HIGH,

the corresponding DQs will be High-Z two clocks later; if the

DQM signal was registered LOW, the DQs will provide valid

data.

WRITE

The WRITE command is used to initiate a burst write

access to an active row. The value on the BA0, BA1 inputs

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

WRITE (continued)

selects the bank, and the address provided on inputs A0-A8

selects the starting column location. The value on input A10

determines whether or not auto precharge is used. If auto pre-

charge is selected, the row being accessed will be precharged at

the end of the WRITE burst; if auto precharge is not selected,

the row will remain open for subsequent accesses. Input data

appearing on the DQs is written to the memory array subject to

the DQM input logic level appearing coincident with the data.

If a given DQM signal is registered LOW, the corresponding

data will be written to memory; if the DQM signal is registered

HIGH, the corresponding data inputs will be ignored, and a

WRITE will not be executed to that byte/column location.

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 speciﬁ ed

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

A10 determines whether one or all banks are to be precharged,

an in the case where only one bank is to be precharged, inputs

BA0, BA1 select the bank. Otherwise BA0, BA1 are treated

as “Don’t Care.” Once 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 which performs the same

individual-bank PRECHARGE functions described above,

without requiring an explicit command. This is accomplished

by using A10 to enable auto precharge in conjunction with a

speciﬁ c 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 full-page burst mode,

where 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. The user must not issue

another command to the same bank until the precharge time

(tRP) is completed. This is determined as if an explicit PRE-

CHARGE command was issued at the earliest possible time,

as described for each burst type in the Operation section of this

data sheet.

BURST TERMINATE

The BURST TERMINATE command is used to truncate

either ﬁ xed-length or full-page bursts. The most recently

registered READ or WRITE command prior to the BURST

TERMINATE command will be truncated, as shown in the

Operation section of this data sheet.

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 non-

persistent, 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 has been met after

the PRECHARGE command as shown in the Operations sec-

tion.

The addressing is generated by the internal refresh con-

troller. This makes the address bits “Don’t Care” during an

AUTO REFRESH command. The 256MB SDRAM requires

8,192 AUTO REFRESH cycles every 64ms (tREF), regardless

of width operation. Providing a distributed AUTO REFRESH

command every 7.81μs will meet the refresh requirement and

ensure that each row is refreshed. Alternatively, 8,192 AUTO

REFRESH commands can be issued in a burst at the minimum

cycle rate (tRFC), once every 64ms (24ms for XT version)

SELF REFRESH (IT & ET Temp options ONLY)

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 and AUTO REFRESH command except CKE

is disabled (LOW). Once the SELF REFRESH command is

registered, all the inputs to the SDRAM become “Don’t Care”

with the exception of CKE, which must remain LOW.

Once self refresh mode is engaged, the SDRAM provides

its own internal clocking, causing it to perform its own AUTO

REFRESH cycles. The SDRAM must remain in self refresh

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

self refresh mode for an indeﬁ nite period beyond that.

The procedure for exiting self refresh requires a sequence

of commands. First, CLK must be stable (stable clock is de-

ﬁ ned as a signal cycling within timing constraints speciﬁ ed

for the clock pin) prior to CKE going back HIGH. Once 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 every 7.81μs or less as both SELF

REFRESH and AUTO REFRESH utilize the row refresh coun-

ter. The SELF REFRESH and AUTO REFRESH option are

available with the IT and ET temperature options. They are

not available with the XT temperature options.

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

OPERATION

BANK/ROW ACTIVA TION

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 (see Figure 3).

After opening a row (issuing an ACTIVE command), a

READ or WRITE command may be issued to that row, sub-

ject to the tRCD speciﬁ cation. 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 com-

mand on which a READ or WRITE command can be entered.

For example, a tRCD speciﬁ cation of 20ns with a 125 MHz

clock (8ns period) results in 2.5 clocks, rounded to 3. This is

reﬂ ected in Figure 4, which covers any case where 2 < tRCD

(MIN)/ tCK < 3. (The same procedure is used to convert

other speciﬁ cation 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 “closed” (precharged). The minimum time interval

between successive ACTIVE commands to the same bank is

deﬁ ned by tRC.

A subsequent ACTIVE command to another bank can be

issued while the ﬁ rst bank is being accessed, which results in

a reduction of total row-access overhead. The minimum time

interval between successive ACTIVE commands to different

banks is deﬁ ned by tRRD.

FIGURE 3: Activating a Speciﬁ c Row

in a Speciﬁ c Bank

FIGURE 4: Example - Meeting tRCD (MIN) When 2 < tRCD (MIN)/ tCK < 3

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

READs

READ bursts are initiated with a READ command, as

shown in Figure 5.

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 enabled,

the row being accessed is precharged at the completion of the

burst. For the generic READ commands used in the following

illustrations, auto precharge is disabled.

During READ bursts, the valid data-out element from the

starting column address will be available following the CAS

latency after the READ command. Each subsequent data-out

element will be valid by the next positive clock edge. Figure 6

shows general timing for each possible CAS latency setting.

Upon completion of a burst, assuming no other commands

have been initiated, the DQs will go High-Z. A full-page burst

will continue until terminated. (At the end of the page, it will

wrap to the start address and continue.)

Data from any READ burst may be truncated with a

subsequent READ command, and data from a ﬁ xed-length

READ burst may be immediately followed by data from a

READ command. In either case, a continuous ﬂ ow of data

can be maintained. The ﬁ rst data element from the new burst

follows either the last element of a complete burst or the last

desired data element of a longer burst that is being truncated.

The new READ command should be issued x cycles before

the clock edge at which the last desired data element is valid,

where x equals the CAS latency minus one. This is shown in

Figure 7 for CAS latencies of two and three; data element n+3

is either the last of a burst of four or the last desired of a longer

burst. The 256MB SDRAM uses a pipelined architecture and

therefore does not require the 2n rule associated with a prefetch

architecture. A READ command can be initiated on any clock

cycle following a previous READ command. Full-speed ran-

dom read accesses can be performed to the same bank, as shown

in Figure 8, or each subsequent READ may be performed to

different bank.

FIGURE 5: READ Command FIGURE 6: CAS Latency

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

FIGURE 7: Consecutive READ Bursts

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

FIGURE 8: Random READ Accesses

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

Data from any READ burst may be truncated with a

subsequent WRITE command, and data from a ﬁ xed-length

READ burst may be immediately followed by data from a

WRITE command (subject to bus turn-around limitations).

The WRITE burst may be initiated on the clock edge imme-

diately 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 may be a possibility that

the device driving the input data will go Low-Z before the

SDRAM DQs 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 Figures 9 and 10. 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 data-out from the

READ. Once the WRITE command is registered, the DQs

will go 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

command. If not, the second WRITE will be an invalid WRITE.

For example, if DQM was LOW during T4 in Figure 10, the

WRITEs at T5 and T7 would be valid, while the WRITE at T6

would be invalid.

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 9 shows the

case where the clock frequency allows for bus contention to

be avoided without adding a NOP cycle, and Figure 10 shows

the case where the additional NOP is needed.

A ﬁ xed-length READ burst may be followed by, or truncat-

ed with, a PRECHARGE command to the same bank (provided

that auto precharge was not activated), and a full-page burst may

be truncated with a PRECHARGE command to the same bank.

The PRECHARGE command should be issued x cycles before

the clock edge at which the last desired data element is valid,

where x equals the CAS latency minus one. This is shown in

Figure 11 for each possible CAS latency; data element n+3 is

either the last of a burst of four or the last desired of a longer

burst. Following the PRECHARGE command, a subsequent

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 ﬁ xed-length burst being executed to com-

pletion, a PRECHARGE command issued at the optimum time

(as described above) provides the same operation that would

result from the same ﬁ xed-length burst with auto precharge.

The disadvantage 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

ﬁ xed-length or full-page bursts.

Full-page READ bursts can be truncated with the BURST

TERMINATE command, and ﬁ xed-length READ bursts may

be truncated with a BURST TERMINATE command, provided

that auto precharge was not activated. The BURST TERMI-

NATE command should be issued x cycles before the clock

edge at which the last desired data element is valid, where x

equals the CAS latency minus one. This is shown in Figure

12 for each possible CAS latency; data element n+3 is the last

desired data element of a longer burst.

FIGURE 9: READ to WRITE FIGURE 10: READ to WRITE With

Extra Clock Cycle

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

FIGURE 11: READ to PRECHARGE

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

FIGURE 12: Terminating a READ Burst

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

WRITEs

WRITE bursts are initiated with a WRITE command, as

shown in Figure 13.

The starting column and blank addresses are provided with

the WRITE command, an auto precharge is either enabled or

disabled for that access. If auto precharge is enabled, the row

being accessed is precharged at the completion of the burst.

For the generic WRITE commands used in the following il-

lustrations, auto precharge is disabled.

During WRITE bursts, the ﬁ rst valid data-in element will be

registered coincident with the WRITE command. Subsequent

data elements will be registered on each successive positive

clock edge. Upon completion of a ﬁ xed-length burst, assum-

ing no other commands have been initiated, the DQs will be

ignored (see Figure 14). A full-page burst will continue until

terminated. (At the end of the page, it will wrap to the start

address and continue.)

Data for any WRITE burst may be truncated with a

subsequent WRITE command, and data for a ﬁ xed-length

WRITE burst may be immediately followed by data for a

WRITE command. The new WRITE command can be issued

on any clock following the previous WRITE command, and the

data provided coincident with the new command applies to the

new command. An example is shown in Figure 15. Data n+1

is either the last of a burst of two or the last desired of a longer

burst. The 256MB SDRAM uses a pipelined architecture and

therefore does not require the 2n rule associated 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 16, or each subsequent WRITE

may be preformed to a different bank.

FIGURE 13: WRITE Command

FIGURE 14: WRITE Burst

FIGURE 15: WRITE to WRITE

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

Data for any WRITE burst may be truncated with a sub-

sequent READ command, and data for a ﬁ xed-length WRITE

burst may be immediately followed by a READ command.

Once the READ command is registered, the data inputs will

be ignored, and WRITEs will not be executed. An example

is shown in Figure 17. Data n+1 is either the last of a burst of

two or the last desired of a longer burst.

Data for a ﬁ xed-length WRITE burst may be followed by,

or truncated with, a PRECHARGE command to the same bank

(provided that auto precharge was not activated), and a full-page

WRITE burst may 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 requires

a tWR of at least one clock plus time, regardless of frequency.

In addition, when truncating a WRITE burst, 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.

An example is shown in Figure 18. Data n+1 is either the last

of a burst of two or the last desired of a longer burst. Following

the PRECHARGE command, a subsequent command to the

same bank cannot be issued until tRP is met. The precharge

can be issued coincident with the ﬁ rst coincident clock edge

(T2 in Figure 18) on an A1 Version and with the second clock

on an A2 Version (Figure 18).

In the case of a ﬁ xed-length burst being executed to com-

pletion, a PRECHARGE command issued at the optimum time

(as described above) provides the same operation that would

result from the same ﬁ xed-length burst with auto precharge.

The disadvantage of the PRECHARGE command is that is

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

ﬁ xed-length or full-page bursts.

FIGURE 16: Random WRITE Cycles

FIGURE 17: WRITE to READ

FIGURE 18: WRITE to PRECHARGE

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

Fixed-length or full-page WRITE bursts can be truncated

with the BURST TERMINATE command. When truncate a

WRITE burst, the input data applied coincident with the BURST

TERMINATE command will be ignored. The last data writ-

ten (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 19, where data n is the last

desired data element of a longer burst.

PRECHARGE

The PRECHARGE command (see Figure 20) 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 some speciﬁ ed 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 to be precharged, inputs BA0, BA1 select the bank. When

all banks are to be precharged, inputs BA0, BA1 are treated as

“Don’t Care”. Once 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.

POWER-DOWN

Power-down occurs if CKE is registered LOW coincident

with a NOP or COMMAND INHIBIT 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 saving while in standby. The device may

not remain in the power-down state longer then the refresh

period (64ms) since no refresh operations are performed in this

mode.

The power-down state is exited by registering a NOP or

COMMAND INHIBIT and CKE HIGH at the desired clock

edge (meeting tCKS). See Figure 21.

FIGURE 20: PRECHARGE Command

FIGURE 19: Terminating a WRITE

Burst

FIGURE 21: Power-Down

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

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 pins at the time of a

suspected internal clock edge is ignored; any data present on

the DQ pins remains driven; and burst counters are not incre-

mented, as long as the clock is suspended. (See examples in

Figure 22 and 23).

Clock suspend more is exited by registering CKE HIGH;

the internal clock and related operation will resume on the

subsequent positive clock edge.

BURST READ/SINGLE WRITE

The burst read/single write mode is entered by program-

ming the write burst mode bit (M9) in the mode register to a

logic 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 sequence, just

as in the normal mode of operation (M9 = 0).

FIGURE 22: Clock Suspend During WRITE Burst

FIGURE 23: Clock Suspend During READ Burst

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

CONCURRENT AUT O PRECHARGE

An access command (READ or WRITE) to another bank

while an access command with auto precharge enabled is

executing is not allowed by SDRAMs, unless the SDRAM

supports CONCURRENT AUTO PRECHARGE. Micross

SDRAMs support CONCURRENT AUTO PRECHARGE.

Four cases where CONCURRENT AUTO PRECHARGE oc-

curs are deﬁ ned below.

READ with Auto Precharge

1. Interrupted by a READ (with or without auto precharge);

A READ to bank m will interrupt a READ on bank n, CAS

latency later. The PRECHARGE to bank n will begin when

the READ to bank m is registered (Figure 24).

2. 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 PRECHARGE to

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

(Figure 25).

FIGURE 24: READ With Auto Precharge Interrupted by a READ

FIGURE 25: READ With Auto Precharge Interrupted by a WRITE

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

WRITE with Auto Precharge

3. 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 CAS latency 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 to bank n will be data-in registered one clock prior to

the READ to bank m (Figure 26).

4. 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 registered.

The last valid data WRITE to bank n will be data registered one

clock prior to the WRITE to bank m (Figure 26).

FIGURE 26: WRITE With Auto Precharge Interrupted by a READ

FIGURE 27: WRITE With Auto Precharge Interrupted by a WRITE

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

TRUTH TABLE 2: CKE1,2,3,4

CKEn-1 CKEn CURRENT STATE COMMANDn ACTIONn NOTES

Power-Down X Maintain Power-Down

Self Refresh X Maintain Self Refresh

Clock Suspend X Maintain Clock Suspend

Power-Down 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 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 Truth Table 3

NOTES:

1. CKEn is the logic state of CKE at clock edge n; CKEn-1 was the state of CKE at the previous 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 once 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 tXSR period.

7. After exiting clock suspend at clock edge n, the device will resume operation and recognize the next command at clock

edge n+1.

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

NOTES:

1. This table applies when CKEn-1 was HIGH and CKEn is HIGH (see Truth Table 2) and after tXSR has been met (if the previ-

ous state was self refresh).

2. This table is bank-speciﬁ c, except where noted, i.e., the current state is for a speciﬁ c bank and the commands shown are those

allowed to be issued to that bank when in that state. Exceptions are covered in the notes below.

3. Current state deﬁ nitions:

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

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 com-

mands, or allowable commands to the other bank should be issued on any clock edge occurring during these states. Allowable

commands to the other bank are determined by its current state and Truth Table 3, and according to Truth Table 4.

Precharging: Starts with registration of a PRECHARGE command and ends when tRP is met. Once 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. Once tRCD is met, the

bank will be in the row active state.

Read w/ Auto

Precharge Enabled: Starts with registration of a READ command with auto precharge enabled and ends when tRP has

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

Write w/ Auto

Precharge Enabled: Starts with registration of a WRITE command with auto precharge enabled and ends when tRP has

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

(continued on next page)

TRUTH TABLE 3: CURRENT STATE BANK n, COMMAND TO BANK n1,2,3,4,5,6

CURRENT STATE CS\ RAS\ CAS\ WE\ COMMAND (ACTION) NOTES

H X X X COMMAND INHIBIT (NOP/Continue previous operation)

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

L L H H ACTIVE (Select and active row)

L L L H AUTO REFRESH 7

LLLLLOAD MODE REGISTER 7

L L H L PRECHARGE 11

L H L H READ (Select column and start READ burst) 10

L H L L WRITE (Select column and start WRITE burst) 10

L L H L PRECHARGE (Deactivate row in bank or banks) 8

L H L H READ (Select column and start new READ burst) 10

L H L L WRITE (Select column and start WRITE burst) 10

L L H L PRECHARGE (Truncate READ burst, start PRECHARGE) 8

L H H L BURST TERMINATE 9

L H L H READ (Select column and start READ burst) 10

L H L L WRITE (Select column and start new WRITE burst) 10

L L H L PRECHARGE (Truncate WRITE burst, start PRECHARGE) 8

L H H L BURST TERMINATE 9

Write

(Auto Precharge

Disabled)

ANY

Idle

Row Active

Read

(Auto Precharge

Disabled)

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

NOTES (continued):

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 tRC is met. Once tRC is

met, the SDRAM will be in the all banks idle state.

Accessing Mode

met. Once tMRD is met, the SDRAM will be in the all banks idle state.

Precharging All: States with registration of a PRECHARGE ALL command and ends when tRP is met. Once 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-speciﬁ c; requires that all banks are idle.

8. May or may not be bank-speciﬁ c; if all banks are to be precharged, all must be in valid state for precharging.

9. Not bank-speciﬁ c; BURST TERMINATE affects the most recent READ or WRITE burst, regardless of bank.

10. READs or WRITEs listed in the Command column include READs or WRITEs with auto precharge enabled and READs

or WRITEs with auto precharge disabled.

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

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

TRUTH TABLE 4: CURRENT STATE BANK n, COMMAND TO BANK m1,2,3,4,5,6

CURRENT STATE CS\ RAS\ CAS\ WE\ COMMAND (ACTION) NOTES

H X X X COMMAND INHIBIT (NOP/Continue previous operation)

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

Idle XXXXAny Command Otherwise Allowed to Bank

L L H H ACTIVE (Select and active 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

L L H H ACTIVE (Select and active 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

L L H H ACTIVE (Select and active 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

L L H H ACTIVE (Select and active 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

L L H H ACTIVE (Select and active 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

Write

(Auto Precharge

Disabled)

Row Activating,

Active, or

Precharging

Read

(with Auto

Precharge)

Write

(with Auto

Precharge)

Any

Read

(Auto Precharge

Disabled)

NOTES:

1. This table applies when CKEn-1 was HIGH and CKEn is HIGH (see Truth Table 2) and after tXSR has been met (if the previ-

ous state was self refresh).

2. This table describes alternate bank operation, except where noted; i.e., the current state is for bank n and the commands shown

are those allowed to be issued to bank m (assuming bank m is in such a state that the given command is allowable). Exceptions

are covered in the notes below.

3. Current state deﬁ nitions:

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

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.

Read w/ Auto

Precharge Enabled: Starts with registration of a READ command with auto precharge enabled and ends when tRP has

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

Write w/ Auto

Precharge Enabled: Starts with registration of a WRITE command with auto precharge enabled and ends when tRP has

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

4. AUTO REFRESH, SELF REFRESH and LOAD MODE REGISTER commands may only be issued 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.. All states and sequences not shown are illegal or reserved. (continued on next page)

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

NOTES (continued):

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 column include READs or WRITEs with auto precharge enabled and

READs or WRITEs with auto precharge disabled.

8. CONCURRENT AUTO PRECHARGE: bank n will initiate the auto precharge command when its burst has been interrupted

by bank m’s burst.

9. Burst in bank n continues as initiated.

10. For a READ without auto precharge interrupted by a READ (with or without auto precharge), the READ to bank m will

interrupt the READ on bank n, CAS latency later (Figure 7).

11. For a READ without auto precharge interrupted by a WRITE (with or without auto precharge), the WRITE to bank m will

interrupt the READ on bank n when registered (Figures 9 and 10). DQM should be used one clock prior to the WRITE com-

mand to prevent bus contention.

12. For a WRITE without auto precharge interrupted by a READ (with or without auto precharge), the READ to bank m will

interrupt the WRITE on bank n when registered (Figure 17), with the data-out appearing CAS latency later. The last valid

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

13. For a WRITE without auto precharge interrupted by a WRITE (with or without auto precharge), the WRITE to bank m will

interrupt the WRITE on bank n when registered (Figure 15). The last valid WRITE to bank n will be data-in registered one

clock prior to the READ to bank m.

14. For a READ with auto precharge interrupted by a READ (with or without auto precharge), the READ to bank m will inter-

rupt the READ on bank n, CAS latency later. The PRECHARGE to bank n will begin when the READ to bank m is registered

(Figure 25).

15. For a READ with auto precharge interrupted by a WRITE (with or without auto precharge), 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 (Figure 25).

16. For a WRITE with auto precharge interrupted by a READ (with or without auto precharge), the READ to bank m will

interrupt the WRITE on bank n when registered, with the data-out appearing CAS latency 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 to bank n will be

data-in registered one clock prior to the READ to bank m (Figure 26).

17. For a WRITE with auto precharge interrupted by a WRITE (with or without auto precharge), 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 prior to the WRITE

to bank m (Figure 27).

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

*Stresses greater than those listed under “Absolute Maximum

Ratings” may cause permanent damage to the device. This

is a stress rating only and functional operation of the device

at these or any other conditions above those indicated in the

operation section of this speciﬁ cation is not implied. Exposure

to absolute maximum rating conditions for extended periods

may affect reliability.

**Junction temperature depends upon package type, cycle

time, loading, ambient temperature and airﬂ ow, and humidity

(plastics).

ABSOLUTE MAXIMUM RATINGS*

Voltage on VDD, VDDQ Supply

Relative to VSS...................................-0.5V to +4.6V

Voltage on Inputs, NC or I/O Pins

Relative to VSS...................................-0.5V to +4.6V

Operating Temperature, TA (IT)......................-40°C to +85°C

Operating Temperature, TA (ET)..................-40°C to +105°C

Operating Temperature, TA (XT)...................-55°C to +125°C

Storage Temperature (plastic).......................-55°C to +150°C

Power Dissipation..............................................................1W

ELECTRICAL CHARACTERISTICS AND RECOMMENDED DC OPERATING CONDITIONS1,5,6

(VDD, VDDQ = +3.3V ±0.3V)

PARAMETER SYMBOL MIN MAX UNITS NOTES

Supply Voltage VDD, VDDQ3 3.6 V

Input High Voltage: Logic 1; All inputs VIH 2.2 VDD+ 0.3 V22

Input Low Voltage: Logic 0; All inputs VIL -0.3 0.8 V 22

Input Leakage Current: Any input 0V < VIN < VDD

(All other pins not under test = 0V) II-5 5 µA

Output Leaka

e Current: DQs are disabled:

0V < VOUT < VDDQIOZ -5 5 µA

Output Levels:

Output High Voltage (IOUT = -4mA) VOH 2.4 --- V

Output Low Voltage (IOUT = 4mA) VOL --- 0.4 V

IDD SPECIFICATIONS AND CONDITIONS1,5,6,11,13 (VDD, VDDQ = +3.3V ±0.3V)

SYMBOL MAX (-75) UNITS NOTES

DD1

140 mA 3, 18,

19, 32

DD2

3mA32

DD3

45 mA 3, 12,

19, 32

DD4

150 mA 3, 18,

19, 32

RFC

= t

RFC

(MIN) I

DD5

300 mA

RFC

= 7.81 µs I

DD6

6mA

Standard I

DD7

4 mA 4, 35

Low Power (L) I

DD7

3mA35

Operatin

Current: Burst Mode; Continuous Burst;

READ or WRITE: All banks active

Auto Refresh Current

CS\ = HIGH; CKE = HIGH

SELF REFRESH CURRENT: CKE < 0.2V

3, 12,

18, 19,

32, 33

PARAMETER

Operatin

Current: Active Mode;

Burst = 2; READ or WRITE; t

= t

(MIN)

Standby Current: Power-Down Mode;

All banks idle; CKE = LOW

Standby Current: Active Mode;

CKE = HIGH; CS\ = HIGH; All banks active after t

RCD

met;

No accesses in progress

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

CAPACITANCE2

PARAMETER SYM MIN MAX UNITS NOTES

Input Capacitance: CLK C

2 4 pF 29

Input Capacitance: All other input-only pins C

2 4 pF 30

Input/Output Capacitance: DQs C

4.0 6.0 pF 31

AC FUNCTIONAL CHARACTERISTICS5,6,7,8,9,11

SYMBOL -75 UNITS NOTES

tCCD 1tCK 17

tCKED 1tCK 14

tPED 1tCK 14

tDQD 0tCK 17

tDQM 0tCK 17

tDQZ 2tCK 17

tDWD 0tCK 17

tDAL 5tCK 15, 21

tDPL 2tCK 16, 21

tBDL 1tCK 17

tCDL 1tCK 17

tRDL 2tCK 16, 21

tMRD 2tCK 26

CL = 3 tROH(3) 3tCK 17

CL = 2 tROH(2) 2tCK 17

PARAMETER

LOAD MODE REGISTER command to ACTIVE or REFRESH command

Data-out to high-impedance from PRECHARGE command

DQM to input data delay

CKE to clock enable or power-down exit setup mode

CKE to clock disable or power-down entry mode

READ/WRITE command to READ/WRITE command

DQM to data high-impedance during READs

WRITE command to input data delay

Data-in to ACTIVE command

DQM to data mask during WRITEs

Last data-in to PRECHARGE command

Last data-in to new READ/WRITE command

Last data-in to burst STOP command

Data-in to PRECHARGE command

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

SYM MIN MA

UNITS NOTES

CL = 3 tAC(3) 5.4 ns 27

CL = 2 tAC(2) 6ns

tAH 0.8 ns

tAS 1.5 ns

tCH 2.5 ns

tCL 2.5 ns

CL = 3 tCK(3) 7.5 ns 23

CL = 2 tCK(2) 10 ns 23

tCKH 0.8 ns

tCKS 1.5 ns

tCMH 0.8 ns

tCMS 1.5 ns

tDH 0.8 ns

tDS 1.5 ns

CL = 3 tHZ(3) 5.4 ns 10

CL = 2 tHZ(2) 6ns10

tLZ 1ns

tOH 3ns

tOHN1.8 ns 28

tRAS 44 80,000 ns

tRC 66 ns

tRCD 20 ns

tREF 64 / 24 ms 34

tRFC 66 ns

tRP 20 ns

tRRD 15 ns

tT0.3 1.2 ns 7

1 CLK +

7.5ns ns 24

15 ns 25

tXSR 75 ns 20, 35

-75

Access time from CLK (pos. edge)

Clock cycle time

Data-out high-impedance time

CS\, RAS\, CAS\, WE\, DQM setup time

CS\, RAS\, CAS\, WE\, DQM hold time

CKE setup time

CKE hold time

Address hold time

Address setup time

tWR

PARAMETER

WRITE recovery time

AUTO REFRESH period

ACTIVE to READ or WRITE delay

Refresh period (8,192 rows)

ACTIVE to ACTIVE command

ACTIVE to PRECHARGE command

Data-out hold time (no load)

CLK high-level width

Exit SELF REFRESH to ACTIVE command

Transition time

ACTIVE bank a to ACTIVE bank b command

PRECHARGE command period

CLK low-level width

Data-out hold time (load)

Data-out low-impedance time

Data-in setup time

Data-in hold time

ELECTRICAL CHARACTERISTICS AND RECOMMENDED AC OPERATING

CONDITIONS5,6,8,9,11

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

NOTES:

1. All voltages referenced to VSS.

2. This parameter is sampled. VDD, VDDQ = +3.3V; f = 1 MHz,

TA = 25°C; pin under test biased at 1.4V.

3. IDD is dependent on output loading and cycle rates. Speci-

ﬁ ed values are obtained with minimum cycle time and the

outputs open.

4. Enables on-chip refresh and address counters.

5. The minimum speciﬁ cations are used only to indicate cycle

time at which proper operation over the full temperature range

is ensured: (0°C < TA < +125°C for XT), (-40°C < TA <

+85°C for IT), and (-45°C < TA < +105°C for ET).

6. 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 si-

multaneously. VSS and VSSQ must be at the same potential.) The

two AUTO REFRESH command wake-ups should be repeated

any time the tREF refresh requirement is exceeded.

7. AC characteristics assume tT = 1ns.

8. In addition to meeting the transition rate speciﬁ cation, the

clock and CKE must transit between VIH and VIL (or between

VIL and VIH) in a monotonic manner.

9. Outputs measured at 1.5V with equivalent load:

10. tHZ deﬁ nes 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. 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 mid-point.

12. Other input signals are allowed to transition no more than

once every two clocks and are otherwise at valid VIH or VIL

levels.

13. IDD speciﬁ cations are tested after the device is properly

initialized.

14. Timing actually speciﬁ ed by tCKS; clock(s) speciﬁ ed as a

reference only at minimum cycle rate.

15. Timing actually speciﬁ ed by tWR plus tRP; clock(s) speciﬁ ed

as a reference only at minimum cycle rate.

16. Timing actually speciﬁ ed by tWR.

17. Required clocks are speciﬁ ed by JEDEC functionality and

are not dependent on any timing parameter.

18. The IDD current will increase or decrease proportionally

according to the amount of frequency alteration for the test

condition.

19. Address transitions average one transition every two

clocks.

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

period.

21. Based on tCK = 7.5ns for -75.

22. VIH overshoot: VIL (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.

23. The clock frequency must remain constant (stable clock is

deﬁ ned as a signal cycling within timing constraints speciﬁ ed

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.

24. Auto precharge mode only. The precharge timing budget

(tRP) begins 7.5ns after the ﬁ rst clock delay, after the last WRITE

is executed. May not exceed limit set for precharge mode.

25. Precharge mode only.

26. JEDEC and PC100 specify three clock.

27. for -75 at CL = 3 with no load is 4.6ns and is guaranteed

by design.

28. Parameter guaranteed by design.

29. PC100 speciﬁ es a maximum of 4pF.

30. PC100 speciﬁ es a maximum of 5pF.

31. PC100 speciﬁ es a maximum of 6.5pF.

32. CL = 3 and tCK = 7.5ns.

33. 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.

34. 64ms refresh for IT, ET temperature options, 24ms refresh

for XT temperature option.

35. Self refresh mode available for IT and ET only.

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

INITIALIZE AND LOAD MODE REGISTER2

TIMING PARAMETERS

MIN MAX MIN MAX

tAH 0.8 ns tCKS 1.5 ns

tAS 1.5 ns tCMH 0.8 ns

tCH 2.5 ns tCMS 1.5 ns

tCL 2.5 ns tMRD

32tCK

tCK(3) 7.5 ns tRFC 66 ns

tCK(2) 10 ns tRP 20 ns

tCKH 0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

*CAS latency indicated in parentheses.

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, with CKE a “Don’t Care”.

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.

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

POWER DOWN MODE1

*CAS latency indicated in parentheses.

NOTES:

1. Violating refresh requirements during power-down may result in loss of data.

TIMING PARAMETERS

MIN MAX MIN MAX

tAH 0.8 ns tCK(2) 10 ns

tAS 1.5 ns tCKH 0.8 ns

tCH 2.5 ns tCKS 1.5 ns

tCL 2.5 ns tCMH 0.8 ns

tCK(3) 7ns

tCMS 1.5 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

CLOCK SUSPEND MODE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 2, the CAS latency = 3, and auto precharge is disabled.

2. A9, A11 and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

AC(3)

5.4 ns t

CKS

1.5 ns

AC(2)

6ns t

CMH

0.8 ns

0.8 ns t

CMS

1.5 ns

1.5 ns t

0.8 ns

2.5 ns t

1.5 ns

2.5 ns t

HZ(3)

5.4 ns

CK(3)

7.5 ns t

HZ(2)

6ns

CK(2)

10 ns t

1ns

CKH

0.8 ns t

3ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

AUTO REFRESH MODE

*CAS latency indicated in parentheses.

TIMING PARAMETERS

MIN MAX MIN MAX

tAH 0.8 ns tCKH 0.8 ns

tAS 1.5 ns tCKS 1.5 ns

tCH 2.5 ns tCMH 0.8 ns

tCL 2.5 ns tCMS 1.5 ns

tCK(3) 7.5 ns tRFC 66 ns

tCK(2) 10 ns tRP 20 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

SELF REFRESH MODE (IT & ET Temp options ONLY)

*CAS latency indicated in parentheses.

NOTES:

1. No maximum time limit for Self Refresh. tRAS(MAX) applied to non-Self Refresh mode.

2. tXSR requires minimum of two clocks regardless of frequency or timing.

TIMING PARAMETERS

MIN MAX MIN MAX

0.8 ns t

CKS

1.5 ns

1.5 ns t

CMH

0.8 ns

2.5 ns t

CMS

1.5 ns

2.5 ns t

RAS

44 80,000 ns

CK(3)

7.5 ns t

20 ns

CK(2)

10 ns t

XSR

75 ns

CKH

0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

READ - WITHOUT AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4, the CAS latency = 2, and the READ burst is followed by a “manual” PRECHARGE.

2. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

AC(3)

5.4 ns t

CMH

0.8 ns

AC(2)

6ns t

CMS

1.5 ns

0.8 ns t

HZ(3)

5.4 ns

1.5 ns t

HZ(2)

6ns

2.5 ns t

1ns

2.5 ns t

3ns

CK(3)

7.5 ns t

RAS

44 80,000 ns

CK(2)

10 ns t

66 ns

CKH

0.8 ns t

RCD

20 ns

CKS

1.5 ns t

20 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

READ - WITH AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4, the CAS latency = 2, and the READ burst is followed by a “manual” PRECHARGE.

2. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

tAC(3) 5.4 ns tCMH 0.8 ns

tAC(2) 6ns tCMS 1.5 ns

tAH 0.8 ns tHZ(3) 5.4 ns

tAS 1.5 ns tHZ(2) 6ns

tCH 2.5 ns tLZ 1ns

tCL 2.5 ns tOH 3ns

tCK(3) 7.5 ns tRAS 44 80,000 ns

tCK(2) 10 ns tRC 66 ns

tCKH 0.8 ns tRCD 20 ns

tCKS 1.5 ns tRP 20 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

SINGLE READ - WITHOUT AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 1, the CAS latency = 2, and the READ burst is followed by a “manual” PRECHARGE.

2. A9, A11, and A12 = “Don’t Care”

3. PRECHARGE command not allowed else tRAS would be violated.

TIMING PARAMETERS

MIN MAX MIN MAX

AC(3)

5.4 ns t

CMH

0.8 ns

AC(2)

6ns t

CMS

1.5 ns

0.8 ns t

HZ(3)

5.4 ns

1.5 ns t

HZ(2)

6ns

2.5 ns t

1ns

2.5 ns t

3ns

CK(3)

7.5 ns t

RAS

44 80,000 ns

CK(2)

10 ns t

66 ns

CKH

0.8 ns t

RCD

20 ns

CKS

1.5 ns t

20 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

SINGLE READ - WITH AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 1, the CAS latency = 2.

2. A9, A11, and A12 = “Don’t Care”

3. READ command not allowed else tRAS would be violated.

TIMING PARAMETERS

MIN MAX MIN MAX

AC(3)

5.4 ns t

CMH

0.8 ns

AC(2)

6ns t

CMS

1.5 ns

0.8 ns t

HZ(3)

5.4 ns

1.5 ns t

HZ(2)

6ns

2.5 ns t

1ns

2.5 ns t

3ns

CK(3)

7.5 ns t

RAS

44 80,000 ns

CK(2)

10 ns t

66 ns

CKH

0.8 ns t

RCD

20 ns

CKS

1.5 ns t

20 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

ALTERNATING BANK READ ACCESSES1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4, the CAS latency = 2.

2. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

tAC(3) 5.4 ns tCMH 0.8 ns

tAC(2) 6ns tCMS 1.5 ns

tAH 0.8 ns tLZ 1ns

tAS 1.5 ns tOH 3ns

tCH 2.5 ns tRAS 44 80,000 ns

tCL 2.5 ns tRC 66 ns

tCK(3) 7.5 ns tRCD 20 ns

tCK(2) 10 ns tRP 20 ns

tCKH 0.8 ns tRRD 15 ns

tCKS 1.5 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

READ - FULL-PAGE BURST1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the CAS latency = 2.

2. A9, A11, and A12 = “Don’t Care”

3. Page left open; no tRP.

TIMING PARAMETERS

MIN MAX MIN MAX

AC(3)

5.4 ns t

CKS

1.5 ns

AC(2)

6ns t

CMH

0.8 ns

0.8 ns t

CMS

1.5 ns

1.5 ns t

HZ(3)

5.4 ns

2.5 ns t

HZ(2)

6ns

2.5 ns t

1ns

CK(3)

7.5 ns t

3ns

CK(2)

10 ns t

RCD

20 ns

CKH

0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

READ - DQM OPERATION1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4, the CAS latency = 2.

2. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

AC(3)

5.4 ns t

CKS

1.5 ns

AC(2)

6ns t

CMH

0.8 ns

0.8 ns t

CMS

1.5 ns

1.5 ns t

HZ(3)

5.4 ns

2.5 ns t

HZ(2)

6ns

2.5 ns t

1ns

CK(3)

7.5 ns t

3ns

CK(2)

10 ns t

RCD

20 ns

CKH

0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

WRITE - WITHOUT AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4, and the WRITE burst is followed by a “manual” PRECHARGE.

2. 14ns to 15ns is required between <DIN m + 3> and the PRECHARGE command, regardless of frequency.

3. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

tAH 0.8 ns tCMS 1.5 ns

tAS 1.5 ns tDH 0.8 ns

tCH 2.5 ns tDS 1.5 ns

tCL 2.5 ns tRAS 44 80,000 ns

tCK(3) 7.5 ns tRC 66 ns

tCK(2) 10 ns tRCD 20 ns

tCKH 0.8 ns tRP 20 ns

tCKS 1.5 ns tWR 15 ns

tCMH 0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

WRITE - WITH AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4.

2. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

tAH 0.8 ns tCMS 1.5 ns

tAS 1.5 ns tDH 0.8 ns

tCH 2.5 ns tDS 1.5 ns

tCL 2.5 ns tRAS 44 80,000 ns

tCK(3) 7.5 ns tRC 66 ns

tCK(2) 10 ns tRCD 20 ns

tCKH 0.8 ns tRP 20 ns

tCKS 1.5 ns tWR

1 CLK +

7.5ns ---

tCMH 0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

SINGLE WRITE - WITHOUT AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 1, and the WRITE burst is followed by a “manual” PRECHARGE.

2. 14ns to 15ns is required between <DIN m> and the PRECHARGE command, regardless of frequency. With a single write tWR has been increased to meet

minimum tRAS requirement.

3. A9, A11, and A12 = “Don’t Care”

4. PRECHARGE command not allowed else tRAS would be violated.

TIMING PARAMETERS

MIN MAX MIN MAX

0.8 ns t

CMS

1.5 ns

1.5 ns t

0.8 ns

2.5 ns t

1.5 ns

2.5 ns t

RAS

44 80,000 ns

CK(3)

7.5 ns t

66 ns

CK(2)

10 ns t

RCD

20 ns

CKH

0.8 ns t

20 ns

CKS

1.5 ns t

15 ns

CMH

0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

SINGLE WRITE - WITH AUTO PRECHARGE1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 1.

2. Requires one clock plus time (7.5ns) with auto precharge or 14ns to 15ns with PRECHARGE.

3. A9, A11, and A12 = “Don’t Care”

4. WRITE command not allowed else tRAS would be violated.

TIMING PARAMETERS

MIN MAX MIN MAX

tAH 0.8 ns tCMS 1.5 ns

tAS 1.5 ns tDH 0.8 ns

tCH 2.5 ns tDS 1.5 ns

tCL 2.5 ns tRAS 44 80,000 ns

tCK(3) 7.5 ns tRC 66 ns

tCK(2) 10 ns tRCD 20 ns

tCKH 0.8 ns tRP 20 ns

tCKS 1.5 ns tWR

1 CLK +

7.5ns ---

tCMH 0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

ALTERNATING BANK WRITE ACCESSES1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4.

2. Requires one clock plus time (7.5ns) with auto precharge or 14ns to 15ns with PRECHARGE.

3. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

0.8 ns t

CMS

1.5 ns

1.5 ns t

0.8 ns

2.5 ns t

1.5 ns

2.5 ns t

RAS

44 80,000 ns

CK(3)

7.5 ns t

66 ns

CK(2)

10 ns t

RCD

20 ns

CKH

0.8 ns t

20 ns

CKS

1.5 ns t

RRD

15 ns

CMH

0.8 ns t

Note 2 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

WRITE - FULL-PAGE BURST

*CAS latency indicated in parentheses.

NOTES:

1. A9, A11, and A12 = “Don’t Care”

2. tWR must be satisﬁ ed prior to PRECHARGE command.

3. Page left open; no tRP.

TIMING PARAMETERS

MIN MAX MIN MAX

0.8 ns t

CKS

1.5 ns

1.5 ns t

CMH

0.8 ns

2.5 ns t

CMS

1.5 ns

2.5 ns t

0.8 ns

CK(3)

7.5 ns t

1.5 ns

CK(2)

10 ns t

RCD

20 ns

CKH

0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

WRITE - DQM OPERATION1

*CAS latency indicated in parentheses.

NOTES:

1. For this example, the burst length = 4.

2. A9, A11, and A12 = “Don’t Care”

TIMING PARAMETERS

MIN MAX MIN MAX

tAH 0.8 ns tCKS 1.5 ns

tAS 1.5 ns tCMH 0.8 ns

tCH 2.5 ns tCMS 1.5 ns

tCL 2.5 ns tDH 0.8 ns

tCK(3) 7.5 ns tDS 1.5 ns

tCK(2) 10 ns tRCD 20 ns

tCKH 0.8 ns

-75

UNITS

-75

SYMBOL* UNITS SYMBOL*

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

MECHANICAL DEFINITIONS

Micross Case #901 (Package Designator DG)

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

MECHANICAL DEFINITIONS

Copper Lead Frame (Cu) (Package Designator DGC)

NOTE :

2. Dimension D and E1 do not include mold protrusion .

3. Dimension b does not include dambar protrusion/intrusion

1. Controlling dimension : mm

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

ORDERING INFORMATION

*AVAILABLE PROCESSES

IT = Industrial Temperature Range -40oC to +85oC

ET = Enhanced Temperature Range -40°C to +105°C

XT = Military Temperature Range -55oC to +125oC

Device Number Package Type Speed Process

AS4SD16M16DG-75/IT 54-pin TSOPII, Alloy 42 lead

frame, PbSn plating 133MHz Industrial

AS4SD16M16DG-75/ET 54-pin TSOPII, Alloy 42 lead

frame, PbSn plating 133MHz Enhanced

AS4SD16M16DG-75/XT 54-pin TSOPII, Alloy 42 lead

frame, PbSn plating 133MHz Military

AS4SD16M16DGC-75/IT 54-pin TSOPII, Cu lead frame,

PbSn plating 133MHz Industrial

AS4SD16M16DGC-75/ET 54-pin TSOPII, Cu lead frame,

PbSn plating 133MHz Enhanced

AS4SD16M16DGC-75/XT 54-pin TSOPII, Cu lead frame,

PbSn plating 133MHz Military

AS4SD16M16DGCR-75/IT 54-pin TSOPII, Cu lead frame,

NiPdAu plating - RoHS 133MHz Industrial

AS4SD16M16DGCR-75/ET 54-pin TSOPII, Cu lead frame,

NiPdAu plating - RoHS 133MHz Enhanced

AS4SD16M16DGCR-75/XT 54-pin TSOPII, Cu lead frame,

NiPdAu plating - RoHS 133MHz Military

SDRAM

AS4SD16M16

Rev. 2.1 4/10

Micross Components reserves the right to change products or speciﬁ cations without notice.

DOCUMENT TITLE

256 MB: 16 Meg x 16 SDRAM Synchronous DRAM Memory

Rev # History Release Date Status

1.7 Text update on pg 8 &34, March 2009 Release

AC Spec update

1.8 Removed “Consult Factory” pg 1 March 2009 Release

1.9 Update Micross Information January 2010 Release

2.0 Added DGC package & April 2010 Release

Copper Lead Frame Information

2.1 Updated Features & Options - Page 1 April 2010 Release

Added Theta symbol on page 3 before jc

Changed all references of IT+ to ET

Updated Maximum Ratings - Page 29