Features
•
•
•
•
•
•
•
•
•
•
2-Wire Serial Interface
Schmitt Trigger, Filtered Inputs For Noise Suppression
DDC1™/ DDC2™ Interface Compliant for Monitor Identification
Low Voltage Operation
– 2.5 (V
CC
= 2.5V to 5.5V)
Internally Organized 128 x 8
100 kHz (2.5V) Compatibility
8-Byte Page Write Mode
Write Protection Available
Self-timed Write Cycle (10 ms max)
High Reliability
– Endurance: 1 Million Write Cycles
– Data Retention: 100 Years
– ESD Protection: >3000V
8-Pin PDIP and JEDEC SOIC Packages
2-Wire Serial
EEPROM
1K (128 x 8)
•
Description
The AT24C21 provides 1024 bits of serial electrically erasable and programmable
read only memory (EEPROM) organized as 128 words of 8 bits each. The device is
optimized for use in applications requiring data storage and serial transmission of con-
figuration and control information. The AT24C21 features two modes of operation:
Transmit-Only Mode and Bidirectional Mode. Upon power-up, the AT24C21 will be in
the Transmit-Only Mode, sending a serial-bit stream of the entire memory contents,
clocked via the VCLK pin. The Bidirectional Mode is selected by a valid high-to-low
transition on the SCL pin and offers byte selectable read/write capability of the entire
memory array. The AT24C21 is available in space saving 8-pin PDIP and 8-pin SOIC
packages.
AT24C21
Pin Configurations
Pin Name
NC
SDA
SCL
VCLK
Function
No Connect
Serial Data
Serial Clock Input
(Bidirectional Mode)
Serial Clock Input
(Transmit-Only Mode)
8-Pin PDIP
8-Pin SOIC
2-Wire, 1K
Serial EEPROM
Rev. 0405E–07/98
1
ATMEL [ ATMEL CORPORATION ]
