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 transmission of configuration and control information. 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 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 Bidirectional 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.

Features:
• Single supply with operation down to 2.5V
• Completely implements DDC1™/DDC2™ interface for monitor identification
• Low-power CMOS technology:
   - 1 mA active current typical
   - 10 µA standby current typical at 5.5V
• 2-wire serial interface bus, I2C™ 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 ensured
• Data retention > 200 years
• 8-pin PDIP and SOIC package
• Available for extended temperature ranges
   Commercial (C): 0°C to +70°C
   Industrial (I): -40°C to +85°C