24LC21A-I Datasheet, PDF (1/18 Pages) Microchip Technology – 1K 2.5V Dual Mode I2C Serial EEPROM

24LC21A
1K 2.5V Dual Mode I²C^™ Serial EEPROM
Features
• Single supply with operation down to 2.5V
• Completely implements DDC1™/DDC2™
interface for monitor identification, including
recovery to DDC1
• Pin and function compatible with 24LC21
• Low-power CMOS technology
- 1 mA typical active current
- 10 µA standby current typical at 5.5V
• 2-wire serial interface bus, I²C™ compatible
• 100 kHz (2.5V) and 400 kHz (5V) compatibility
• Self-timed write cycle (including auto-erase)
• Page write buffer for up to eight bytes
• 1,000,000 erase/write cycles ensured
• Data retention > 200 years
• ESD Protection > 4000V
• 8-pin PDIP and SOIC package
• Available for extended temperature ranges
- Commercial (C):
- Industrial (I):
0°C to +70°C
-40°C to +85°C
Description
The Microchip Technology Inc. 24LC21A is a 128 x 8-bit
dual-mode Electrically Erasable PROM. This device is
designed for use in applications requiring storage and
serial transmission of configuration and control informa-
tion. Two modes of operation have been implemented:
Transmit-only mode and Bidirectional mode. Upon
power-up, the device will be in the Transmit-only mode,
sending a serial bit stream of the memory array from 00h
to 7Fh, clocked by the VCLK pin. A valid high-to-low
transition on the SCL pin will cause the device to enter
the transition mode, and look for a valid control byte on
the I²C bus. If it detects a valid control byte from the
master, it will switch into Bidirectional mode, with byte
selectable read/write capability of the memory array
using SCL. If no control byte is received, the device will
revert to the Transmit-only mode after it receives 128
consecutive VCLK pulses while the SCL pin is idle. The
24LC21A is available in a standard 8-pin PDIP and
SOIC package in both commercial and industrial
temperature ranges.
DDC is a trademark of the Video Electronics Standards
Association.
I²C is a trademark of Philips Corporation.
Package Types
PDIP
NC 1
NC 2
NC 3
VSS 4
SOIC
NC ¹
NC ²
NC ³
Vss ⁴
8 Vcc
7 VCLK
6 SCL
5 SDA
8
Vcc
7
VCLK
6
SCL
5
SDA
Block Diagram
I/O
Control
Logic
Memory
Control
Logic
XDEC
SDA SCL
VCLK
VCC
VSS
HV Generator
EEPROM
Array
Page Latches
YDEC
Sense AMP
R/W Control
Pin Function Table
Name
VSS
SDA
SCL
VCLK
VCC
NC
Function
Ground
Serial Address/Data I/O
Serial Clock (Bidirectional mode)
Serial Clock (Transmit-only mode)
+2.5V to 5.5V Power Supply
No Connection
 2003 Microchip Technology Inc.
DS21160F-page 1