24CSM01 1Mbit Serial EEPROMs Microchip Technology 24CSM01 1-Mbit Serial EEPROMs are capable of speeds up to 3.4MHz and operate from 1.7V to 5.5V voltage range. These serial EEPROMs allow up to eight devices to share a common I2C (two-wire) bus. The 24CSM01 EEPROMs are organized as 131,072 bytes of 8 bits each (128Kbytes) and optimized for consumer and industrial applications. These EEPROMs feature a 4Kbit security register and the first half is read-only. The security register contains a factory-programmed, ensured unique, and 128-bit serial number in the first 16 bytes.