24LCS21A

The Microchip Technology Inc. 24LCS21A 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 con?guration 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 memory array from 00h to 7Fh, clocked by the VCLK pin. A valid high to low transition on the SCL pin will cause 24LCS21A 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 Bi-directional 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 24LCS21A also enables the user to write-protect the entire memory array using its write-protect pin. The 24LCS21A is available in a standard 8-pin PDIP and SOIC package in both commercial and industrial temperature ranges.