ST24LC21

1Kb (x8) DUAL MODE SERIAL EEPROM

for VESA Plug&Play

NOT FOR NEW DESIGN

June 1997

1/18

This is information on a product still in production but not recommended for new designs.

1 MILLION ERASE/WRITE CYCLES

40 YEARS DATA RETENTION

2.5V to 5.5V SINGLE SUPPLY VOLTAGE

400k Hz COMPATIBILITY OVER the FULL

RANGE of SUPPLY VOLTAGE

COMPATIBLE

PAGE WRITE (up to 8 BYTES)

BYTE, RANDOM and SEQUENTIAL READ

MODES

SELF TIMED PROGRAMMING CYCLE

AUTOMATIC ADDRESS INCREMENTING

ENHANCED ESD/LATCH UP

PERFORMANCES

ST24LC21 is replaced by the ST24LC21B

DESCRIPTION

The ST24LC21 is a 1K bit electrically erasable

programmable memory (EEPROM), organized by

8 bits.This device can operate in two modes: Trans-

powered, the device is in Transmit Only mode with

EEPROM data clocked out from the rising edge of

the signal applied on VCLK.

upon the falling edge of the signal applied on SCL

bidirectional mode to the Transmit Only mode (ex-

cept when the power supply is removed). The

device operates with a power supply value as low

as 2.5V. Both Plastic Dual-in-Line and Plastic Small

Outline packages are available.

AI01489

SDA

VCC

ST24LC21

VCLK

SCL

VSS

Figure 1. Logic Diagram

SDA

Serial Data Address Input/Output

SCL

Serial Clock (I

Supply Voltage

Ground

VCLK

Clock Transmit only mode

Table 1. Signal Names

8

1

SO8 (M)

8

1

PSDIP8 (B)

0.25mm Frame