The CAT25040 is a EEPROM Serial 4-Kb SPI device internally organized as 512x8 bits. ON Semiconductor's advanced CMOS Technology substantially reduces device power requirements. It features a 16-byte page write buffer and supports the Serial Peripheral Interface (SPI) protocol. The device is enabled though a Chip Select (CS). In addition, the required bus signalsare a clock input (SCK), data input (SI) and data output (SO) lines. TheHOLDinput may be used to pause any serial communication with the CAT25040 device. This device features software and hardware write protection, including partial as well as full array protection.