Integrated Silicon Solution, Inc. — 1-800-379-4774

1

REV. A

11/01/01

IS23SC4418

IS23SC4428

ISSI reserves the right to make changes to its products at any time without notice in order to improve design and supply the best possible product. We assume no responsibility for any errors

which may appear in this publication. © Copyright 1999, Integrated Silicon Solution, Inc.

IS23SC4418

IS23SC4428

1-KBYTE EEPROM

WITH WRITE PROTECT FUNCTION AND

PROGRAMMABLE SECURITY CODE (PSC)

NOVEMBER 2001

FEATURES

• Standard CMOS process

• 1024 x 8 bits EEPROM organization

• Byte-wise addressing

• Byte-wise erase/write

• Irreversible byte-wise write protection

• Single 5V power supply for read and write/erase

• Low power operation:

– 3 mA typical active current

• 5 ms programming time

• 3-wire serial interface

• 20 KHz serial clock rate

• Contact configuration and serial interface,

ISO standard 7816 (Synchronous Transmission)

compatible.

• High ESD protection: > 4 KV

• High reliability:

– 1,000,000 erase/write cycles guaranteed

– 10 years data retention

• Wide operating temperature range

– 0 to +70°C Commercial; –40 to +85°C Industrial

Additional feature of IS23SC4428:

• 2-byte Programmable Security Code (PSC) for

memory write/erase protection

DESCRIPTION

IS23SC4418

IS23SC4418 contains 1024 x 8 bits of EEPROM with

programmable write protection for each byte. Random

read access to any byte in the memory is always possible.

The memory can also be erased and written byte by byte.

Erasing old data in the byte location must be performed

before new data can be written to the location. Each byte

in the memory has a corresponding protect bit. The

protect bits are only one-time programmable and cannot

be erased. After the protect bits are enabled (logic 0), the

corresponding bytes can never be changed again. A write-protect

bit with data-compare function is available for user to

verify the data in the memory before enabling the protect bit.

IS23SC4428

IS23SC4428 offers all the features in IS23SC4418. In

addition, it offers two bytes of Programmable Security

Code (PSC) against unauthorized memory write/erase

operations. All the memory, except for the PSC can

always be read, but the memory can be written or erased

only after PSC verification. If the user fails to enter the

correct PSC in eight consecutive attempts, the device will

block any further PSC entry attempts and the memory can

never be erased or written again.

The PSC bytes are pre-programmed by the manufacturer

with a code, which is specified for the customer for device

transport security purposes, before the devices are shipped

to the customer. The Error Counter will be pre-erased by

the manufacturer to allow maximum attempts (maximum

of eight) for PSC entry.