AT24C21_03 Datasheet, PDF (1/17 Pages) ATMEL Corporation – 2-wire Serial EEPROM

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
• 8-lead PDIP and 8-lead JEDEC SOIC Packages
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-lead PDIP and 8-lead
JEDEC SOIC packages.
2-wire Serial
EEPROM
1K (128 x 8)
AT24C21
Not Recommended
for New Designs
Pin Configurations
Pin Name Function
NC
No Connect
SDA
SCL
VCLK
Serial Data
Serial Clock Input
(Bidirectional Mode)
Serial Clock Input
(Transmit-only Mode)
8-lead PDIP
NC 1
NC 2
NC 3
GNE 4
8 VCC
7 VCLK
6 SCL
5 SDA
2-Wire, 1K
Serial EEPROM
8-lead SOIC
NC 1
NC 2
NC 3
GND 4
8 VCC
7 VCLK
6 SCL
5 SDA
Rev. 0405I–SEEPR–7/03
1