DS2430A+T&R - Maxim Integrated Products, Inc.

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FEATURES

§ 256-bit Electrically Erasable Programmable

Read Only Memory (EEPROM) plus 64-bit

one-time programmable application register

§ Unique, factory-lasered and tested 64-bit

registration number (8-bit family code + 48-bit

serial number + 8-bit CRC tester) assures

absolute identity because no two parts are alike

§ Built-in multidrop controller ensures

compatibility with other MicroLAN products

§ EEPROM organized as one page of 32 bytes

for random access

§ Reduces control, address, data, and power to a

single data pin

§ Directly connects to a single port pin of a

microprocessor and communicates at up to

16.3kbits per second

§ 8-bit family code specifies DS2430A

communication requirements to reader

§ Presence detector acknowledges when reader

first applies voltage

§ Low cost TO-92 or 6-pin TSOC surface mount

package

§ Reads and writes over a wide voltage range of

2.8V to 6.0V from -40°C to +85°C

ORDERING INFORMATION

DS2430A TO-92 package

DS2430AP 6-pin TSOC package

DS2430A/T&R Tape & Reel version of

DS2430A

DS2430AP/T&R Tape & Reel version of

DS2430AP

DS2430AX Chip Scale Pkg., 10k Tape

& Reel

DS2430AX-S Chip Scale Pkg., 2.5k Tape

& Reel

PIN ASSIGNMENT

PIN DESCRIPTION

TO-92 TSOC

Pin 1 Ground Ground

Pin 2 Data Data

Pin 3 NC NC

Pin 4 –––– NC

Pin 5 –––– NC

Pin 6 ––––

DS2430

256-Bit 1-Wire EEPROM

www.maxim-ic.com

TOP VIEW

3.7mm x 4.0mm x 1.5mm

SIDE VIEW

See Mech.

Drawing Section

TSOC PACKAGE

BOTTOM VIEW

See Mech.

Drawings Section

TO-92

DALLAS

DS2430A

2 3

1 2 3

DS2430A

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SILICON LABEL DESCRIPTION

The DS2430A 256-bit 1-Wire EEPROM identifies and stores relevant information about the product to

which it is associated. This lot or product specific information can be accessed with minimal interface, for

example a single port pin of a microcontroller. The DS2430A consists of a factory-lasered registration

number that includes a unique 48-bit serial number, an 8-bit CRC, and an 8-bit Family Code (14h) plus

256 bits of user-programmable EEPROM and a 64-bit one-time programmable application register. The

power to read and write the DS2430A is derived entirely from the 1-Wire® communication line. Data is

transferred serially via the 1-Wire protocol, which requires only a single data lead and a ground return.

The 48-bit serial number that is factory-lasered into each DS2430A provides a guaranteed unique identity

that allows for absolute traceability. The TO-92 and TSOC packages provide a compact enclosure that

allows standard assembly equipment to handle the device easily for attachment to printed circuit boards

or wiring. Typical applications include storage of calibration constants, board identification, and product

revision status.

OVERVIEW

The block diagram in Figure 1 shows the relationships between the major control and memory sections of

the DS2430A. The DS2430A has four main data components: 1) 64-bit lasered ROM, 2) 256-bit

EEPROM data memory with scratchpad, 3) 64-bit one-time programmable application register with

scratchpad and 4) 8-bit status memory. The hierarchical structure of the 1-Wire protocol is shown in

Figure 2. The bus master must first provide one of the four ROM Function Commands: 1) Read ROM, 2)

Match ROM, 3) Search ROM, 4) Skip ROM. The protocol required for these ROM Function Commands

is described in Figure 8. After a ROM Function Command is successfully executed, the memory

functions become accessible and the master can provide any one of the four memory function commands.

The protocol for these memory function commands is described in Figure 6. All data is read and written

least significant bit first.

64-BIT LASERED ROM

Each DS2430A contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code

(14h). The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. (Figure

3). The 1-Wire CRC is generated using a polynomial generator consisting of a shift register and XOR

gates as shown in Figure 4. The polynomial is X8 + X5 + X4 + 1. Additional information about the Dallas

1-Wire Cyclic Redundancy Check is available in the Book of DS19xx iButton® Standards. The shift

time is shifted in. After the 8th bit of the family code has been entered, then the serial number is entered.

After the 48th bit of the serial number has been entered, the shift register contains the CRC value. Shifting

in the 8 bits of CRC should return the shift register to all 0s.

1-Wire and iButton are registered trademarks of Dallas Semiconductor.

DS2430A

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DS2430A BLOCK DIAGRAM Figure 1

DS2430A

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HIERARCHICAL STRUCTURE FOR 1-WIRE PROTOCOL Figure 2

64-BIT LASERED ROM Figure 3

8-Bit CRC Code 48-Bit Serial Number 8-Bit Family Code (14H)

MSB LSB MSB LSB MSB LSB

1-WIRE CRC GENERATOR Figure 4

Polynomial = X8 + X5 + X4 + 1

DS2430A

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MEMORY

The memory of the DS2430A consists of three separate sections, called data memory, application

intermediate storage area called scratchpad that acts as a buffer when writing to the device. The data

memory can be read and written as often as desired. The application register, however, is one-time

programmable only. Once the application register is programmed, it is automatically write protected. The

status register will indicate if the application register is already locked or if it is still available for storing

data. As long as the application register is unprogrammed, the status register will read FFh. Copying data

from the register scratchpad to the application register will clear the 2 least significant bits of the status

DS2430A MEMORY MAP Figure 5

MEMORY FUNCTION COMMANDS

The Memory Function Flow Chart (Figure 6) describes the protocols necessary for accessing the different

memory sections of the DS2430A. An example is shown later in this document.

WRITE SCRATCHPAD [0Fh]

After issuing the Write Scratchpad command, the master must first provide a 1-byte address, followed by

the data to be written to the scratchpad for the data memory. The DS2430A will automatically increment

the address after every byte it received. After having received a data byte for address 1Fh, the address

counter will wrap around to 00h for the next byte and writing continues until the master sends a Reset

Pulse.

READ SCRATCHPAD [AAh]

This command is used to verify data previously written to the scratchpad before it is copied into the final

storage EEPROM memory. After issuing the Read Scratchpad command, the master must provide the 1-

byte starting address from where data is to be read. The DS2430A will automatically increment the

address after every byte read by the master. After the data of address 1Fh has been read, the address

counter will wrap around to 00h for the next byte and reading continues until the master sends a Reset

Pulse.

DS2430A

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MEMORY FUNCTION FLOW CHART Figure 6

COPY SCRATCHPAD [55h]

After the data stored in the scratchpad has been verified the master may send the Copy Scratchpad

command followed by a validation key of A5h to transfer data from the scratchpad to the EEPROM

memory. This command will always copy the data of the entire scratchpad. Therefore, if one desires to

change only a few bytes of the EEPROM data, the scratchpad should contain a copy of the latest

EEPROM data before the Write Scratchpad and Copy Scratchpad commands are issued. After this

command is issued, the data line must be held at logic high level for at least 10ms.

READ MEMORY [F0h]

The Read Memory command is used to read a portion or all of the EEPROM data memory and to copy

the entire data memory into the scratchpad to prepare for changing a few bytes. To copy data from the

data memory to the scratchpad and to read it, the master must issue the read memory command followed

by the 1-byte starting address from where data is to be read from the scratchpad. The DS2430A will

automatically increment the address after every byte read by the master. After the data of address 1Fh has

been read, the address counter will wrap around to 00h for the next byte and reading continues until the

master sends a Reset Pulse. If one intends to copy the entire data memory to the scratchpad without

reading data, a starting address is not required; the master may send a Reset Pulse immediately following

the command code.

DS2430A

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MEMORY FUNCTION FLOW CHART Figure 6 (cont’d)

WRITE APPLICATION REGISTER [99h]

This command is essentially the same as the Write Scratchpad command, but it addresses the 64-bit

by the data to be written. The DS2430A will automatically increment the address after every byte it

received. After having received a data byte for address 07h, the address counter will wrap around to 00h

for the next byte and writing continues until the master sends a Reset Pulse. The Write Application

device with the application register locked, the data written to the register scratchpad will be lost.

READ STATUS REGISTER [66h]

The status register is a means for the master to find out if the application register has been programmed

and locked. After issuing the read status register command, the master must provide the validation key

00h before receiving status information. The two least significant bits of the 8-bit status register will be 0

if the application register was programmed and locked; all other bits will always read 1. The master may

finish the read status command by sending a Reset Pulse at any time.

DS2430A

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MEMORY FUNCTION FLOW CHART Figure 6 (cont’d)

READ APPLICATION REGISTER [C3h]

This command is used to read the application register or the register scratchpad. As long as the

application register is not yet locked, one will receive data from the register scratchpad. After the

application register is locked the DS2430A will transmit data from the application register, making the

received with this command came from. After issuing the Read Application Register command, the

master must provide the 1-byte starting address from where data is to be read. The DS2430A will

automatically increment the address after every byte read by the master. After the data of address 07h has

been read, the address counter will wrap around to 00h for the next byte and reading continues until the

master sends a Reset Pulse.

COPY & LOCK APPLICATION REGISTER [5Ah]

After the data stored in the register scratchpad has been verified the master may send the Copy & Lock

Application Register command followed by a validation key of A5h to transfer the contents of the entire

cancel this command by sending a Reset Pulse instead of the validation key. After the validation key was

transmitted, the application register will contain the data of the register scratchpad. Further write accesses

to the application register will be denied. The Copy & Lock Application Register command can only

be executed once.

DS2430A

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1-WIRE BUS SYSTEM

The 1-Wire bus is a system that has a single bus master and one or more slaves. In all instances, the

DS2430A is a slave device. The bus master is typically a microcontroller. The discussion of this bus

system is broken down into three topics: hardware configuration, transaction sequence, and 1-Wire

signaling (signal type and timing). A 1-Wire protocol defines bus transactions in terms of the bus state

during specified time slots that are initiated on the falling edge of sync pulses from the bus master. For a

more detailed protocol description, refer to Chapter 4 of the Book of DS19xx iButton Standards.

Hardware Configuration

The 1-Wire bus has only a single line by definition; it is important that each device on the bus be able to

drive it at the appropriate time. To facilitate this, each device attached to the 1-Wire bus must have open

drain connection or three-state outputs. The 1-Wire port of the DS2430A is open drain with an internal

circuit equivalent to that shown in Figure 7. A multidrop bus consists of a 1-Wire bus with multiple

slaves attached. The DS2430A communicates at regular 1-Wire speed, 16.3kbits per second, and requires

a pullup resistor as shown in Figure 7. The idle state for the 1-Wire bus is high. If for any reason a

transaction needs to be suspended, the bus MUST be left in the idle state if the transaction is to resume. If

this does not occur and the bus is left low for more than 120µs, one or more of the devices on the bus may

be reset.

HARDWARE CONFIGURATION Figure 7

Note: Depending on the 1-Wire communication speed and the bus characteristics, the optimal pullup

resistor value will be in the 1.5kW to 5kW range. To write to a single device, a 2.2kW resistor and VPUP of

at least 4.0V is sufficient. For writing multiple DS2430As simultaneously or operation at low VPUP, the

resistor should be bypassed by a low-impedance pullup to VPUP while the device copies the scratchpad to

EEPROM.

RPU

DS2430A

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ROM FUNCTIONS FLOW CHART Figure 8

DS2430A

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Transaction Sequence

The sequence for accessing the DS2430A via the 1-Wire port is as follows:

§ Initialization

§ ROM Function Command

§ Memory Function Command

§ Transaction/Data

INITIALIZATION

All transactions on the 1-Wire bus begin with an initialization sequence. The initialization sequence

consists of a Reset Pulse transmitted by the bus master followed by a Presence Pulse(s) transmitted by the

slave(s).

The Presence Pulse lets the bus master know that the DS2430A is on the bus and is ready to operate. For

more details, see the 1-Wire Signaling section.

ROM FUNCTION COMMANDS

Once the bus master has detected a presence, it can issue one of the four ROM function commands. All

ROM function commands are 8 bits long. A list of these commands follows (refer to flowchart in Figure

8):

Read ROM [33h]

This command allows the bus master to read the DS2430A’s 8-bit family code, unique 48-bit serial

number, and 8-bit CRC. This command can be used only if there is a single DS2430A on the bus. If more

than one slave is present on the bus, a data collision will occur when all slaves try to transmit at the same

time (open drain will produce a wired-AND result). The resultant family code and 48-bit serial number

will usually result in a mismatch of the CRC.

Match ROM [55h]

The Match ROM command, followed by a 64-bit ROM sequence, allows the bus master to address a

specific DS2430A on a multidrop bus. Only the DS2430A that exactly matches the 64-bit ROM sequence

will respond to the subsequent memory function command. All slaves that do not match the 64-bit ROM

sequence will wait for a Reset Pulse. This command can be used with a single or multiple devices on the

bus.

Skip ROM [CCh]

This command can save time in a single-drop bus system by allowing the bus master to access the

memory functions without providing the 64-bit ROM code. If more than one slave is present on the bus

and a read command is issued following the Skip ROM command, data collision will occur on the bus as

multiple slaves transmit simultaneously (open drain pulldowns will produce a wired-AND result).

Search ROM [F0h]

When a system is initially brought up, the bus master might not know the number of devices on the 1-

Wire bus or their 64-bit ROM codes. The Search ROM command allows the bus master to use a process

of elimination to identify the 64-bit ROM codes of all slave devices on the bus. The Search ROM process

is the repetition of a simple, three-step routine: read a bit, read the complement of the bit, then write the

desired value of that bit. The bus master performs this simple, three-step routine on each bit of the ROM.

DS2430A

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After one complete pass, the bus master knows the contents of the ROM in one device. The remaining

number of devices and their ROM codes may be identified by additional passes. See Chapter 5 of the

Book of DS19xx iButton Standards for a comprehensive discussion of a search ROM, including an actual

example.

1-Wire Signaling

The DS2430A requires strict protocols to insure data integrity. The protocol consists of four types of

signaling on one line: Reset Sequence with Reset Pulse and Presence Pulse, Write 0, Write 1 and Read

Data. All these signals (except Presence Pulse) are initiated by the bus master. The initialization sequence

required to begin any communication with the DS2430A is shown in Figure 9. A Reset Pulse followed by

a Presence Pulse indicates the DS2430A is ready to accept a ROM command. The bus master transmits

(TX) a Reset Pulse (tRSTL, minimum 480µs). The bus master then releases the line and goes into receive

mode (RX). The 1-Wire bus is pulled to a high state via the pullup resistor. After detecting the rising edge

on the data pin, the DS2430A waits (tPDH, 15µs to 60µs) and then transmits the Presence Pulse (tPDL, 60µs

to 240µs).

INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” Figure 9

In order not to mask interrupt signaling by other devices on the 1-Wire bus, tRSTL + tR should always be

less than 960µs.

Read/Write Time Slots

The definitions of write and read time slots are illustrated in Figure 10. All time slots are initiated by the

master driving the data line low. The falling edge of the data line synchronizes the DS2430A to the

master by triggering a delay circuit in the DS2430A. During write time slots, the delay circuit determines

when the DS2430A will sample the data line. For a read data time slot, if a “0” is to be transmitted, the

delay circuit determines how long the DS2430A will hold the data line low overriding the 1 generated by

the master. If the data bit is a “1”, the DS2430A will leave the read data time slot unchanged.

DS2430A

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READ/WRITE TIMING DIAGRAM Figure 10

Write-0 Time Slot

Write-1 Time Slot

Read-data Time Slot

DS2430A

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MEMORY FUNCTION EXAMPLE

Example: Write 2 data bytes to data memory location 0006 and 0007. Read entire data memory.

MASTER MODE DATA (LSB FIRST) COMMENTS

TX Reset Reset pulse (480µs to 960µs)

RX Presence Presence pulse

TX CCh Issue “Skip ROM” command

TX 0Fh Issue “Write Scratchpad” command

TX 06h Start address = 06h

TX <2 Data Bytes> Write 2 bytes of data to scratchpad

TX Reset Reset pulse

RX Presence Presence pulse

TX CCh Issue “Skip ROM” command

TX AAh Issue “Read Scratchpad” command

TX 06h Start address = 06h

RX <2 Data Bytes> Read scratchpad data and verify

TX Reset Reset pulse

RX Presence Presence pulse

TX CCh Issue “Skip ROM” command

TX 55h Issue “Copy Scratchpad” command

TX A5h Validation key

TX <Data Line High>

Data line is held high for 10ms by the bus master to

provide energy for copying data from the scratchpad to

EEPROM

TX Reset Reset pulse

RX Presence Presence pulse

TX CCh Issue “Skip ROM” command

TX F0h Issue “Read Memory” command

TX 00h Start address = 00h

RX <32 Bytes> Read EEPROM data page

TX Reset Reset pulse

RX Presence Presence pulse

DS2430A

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ABSOLUTE MAXIMUM RATINGS*

Voltage on DATA to Ground -0.5V to +7.0V

Operating Temperature Range -40°C to +85°C

Storage Temperature Range -55°C to +125°C

Soldering Temperature See J-STD-020A Specification

* This is a stress rating only and functional operation of the device at these or any other conditions

above those indicated in the operation sections of this specification is not implied. Exposure to

absolute maximum rating conditions for extended periods of time may affect reliability.

DC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VPUP = 2.8V to 6.0V)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Logic 1 VIH 2.2 V 1, 6

Logic 0 VIL -0.3 +0.8 V 1, 9

Output Logic Low @ 4mA VOL 0.4 V 1

Output Logic High VOH V

PUP 6.0 V 1, 2

Input Load Current (DATA pin) IL 5 mA 3

Programming Current IP 500 mA

CAPACITANCE (tA = +25°C)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Capacitance CD 800 pF 7

ENDURANCE (VPUP = 5.0V; tA = +25°C)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Write/Erase Cycles NCYCLE 100k - 10

AC ELECTRICAL CHARACTERISTICS (-40°C to +85°C; VPUP=2.8V to 6.0V)

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Time Slot tSLOT 60 120 µs

Write 1 Low Time tLOW1 1 15 µs 13

Write 0 Low Time tLOW0 60 120 µs

Read Low Time tLOWR 1 15 µs 13

Read Data Valid tRDV 15 µs 11, 12

Release Time tRELEASE 0 15 45 µs

Read Data Setup tSU 1 µs 5

Recovery Time tREC 1 µs

Reset Time High tRSTH 480 µs 4

Reset Time Low tRSTL 480 960 µs 8

Presence Detect High tPDH 15 60 µs

Presence Detect Low tPDL 60 240 µs

Programming Time tPROG 10 ms

DS2430A

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NOTES:

1) All voltages are referenced to ground.

2) VPUP = external pullup voltage.

3) Input load is to ground.

4) An additional reset or communication sequence cannot begin until the reset high time has expired.

5) Read data setup time refers to the time the host must pull the 1-Wire bus low to read a bit. Data is

guaranteed to be valid within 1ms of this falling edge.

6) VIH is a function of the external pullup resistor and VPUP.

7) Capacitance on the data pin could be 800pF when power is first applied. If a 5kW resistor is used to

pull up the data line to VPUP, 5ms after power has been applied the parasite capacitance will not affect

normal communications.

8) The Reset Low Time (tRSTL) should be restricted to a maximum of 960µs, to allow interrupt signaling;

otherwise it could mask or conceal interrupt pulses.

9) Under certain low voltage conditions VILMAX may have to be reduced to as much as 0.5V to always

guarantee a Presence Pulse.

10) The Copy Scratchpad takes 10ms maximum, during which the voltage on the 1-Wire bus must not fall

below 2.8V.

11) Depending on the 1-Wire communication speed and the bus load characteristics, the optimal pullup

resistor value will be in the 1.5kW to 5kW range.

12) The optimal sampling point for the master is as close as possible to the end time of the 15µs tRDV

period without exceeding tRDV. For the case of a Read-One Time slot, this maximizes the amount of

time for the pullup resistor to recover to a high level. For a Read-Zero Time slot, it ensures that a read

will occur before the fastest 1-Wire device(s) releases the line.

13) The duration of the low pulse sent by the master should be a minimum of 1µs with a maximum value

as short as possible to allow time for the pullup resistor to recover the line to a high level before the 1-

Wire device samples in the case of a Write-One Time or before the master samples in the case of a

Read-One Time.