© 1996 Microchip Technology Inc.

DS21095F-page 1

FEATURES

• Single supply with operation down to 2.5V

• Completely implements DDC1

™/DDC2™ inter-

face for monitor identification

• Low power CMOS technology

- 1 mA active current typical

- 10

µA standby current typical at 5.5V

™ compatible

• Self-timed write cycle (including auto-erase)

• Page-write buffer for up to 8 bytes

• 100 kHz (2.5V) and 400 kHz (5V) compatibility

• Factory programming (QTP) available

• 1,000,000 erase/write cycles guaranteed

• Data retention > 200 years

• 8-pin PDIP and SOIC package

• Available for extended temperature ranges

DESCRIPTION

The Microchip Technology Inc. 24LC21 is a 128 x 8 bit

Electrically Erasable PROM. This device is designed for

use in applications requiring storage and serial trans-

mission of configuration and control information. Two

modes of operation have been implemented: Transmit

Only Mode and Bi-Directional Mode. Upon power-up,

the device will be in the Transmit Only Mode, sending a

serial bit stream of the entire memory array contents,

clocked by the VCLK pin. A valid high to low transition

on the SCL pin will cause the device to enter the

Bi-Directional Mode, with byte selectable read/write

capability of the memory array. The 24LC21 is available

in a standard 8-pin PDIP and SOIC package in both

commercial and industrial temperature ranges.

- Commercial (C):

0˚C to +70˚C

- Industrial (I):

-40˚C to +85˚C

PACKAGE TYPES

BLOCK DIAGRAM

NC

NC

NC

1

2

3

4

8

7

6

5

VCLK

SCL

SDA

NC

NC

NC

1

2

3

4

8

7

5

5

VCLK

SCL

SDA

PDIP

SOIC

HV GENERATOR

EEPROM

ARRAY

PAGE LATCHES

YDEC

XDEC

SENSE AMP

R/W CONTROL

MEMORY

CONTROL

LOGIC

I/O

CONTROL

LOGIC

VCLK

SDA

SCL

24LC21

DDC is a trademark of the Video Electronics StandarDs Association.

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