The 25AA040-I/P is a 4Kbit (512Byte) Serial EEPROM from Microchip. It is an 8-Pin Serial Electrically-Erasable Programmable Read-Only Memory (EEPROM), which operates from a single 2.7V to 5.5V supply with a maximum operating frequency of 10MHz. This Serial EEPROM uses the Microchip proprietary serial protocol for both address and data transfer and supports a two-wire interface compatible with the standard Serial Peripheral Interface (SPI) or the industry standard three-wire Microwire interface. The 25AA040-I/P is provided in an 8-pin PDIP, SOIC, and MSOP packages and is available in standard, industrial, and extended temperature range options. It has a low power consumption of 1mW standby and 8mW maximum active and features write protection, hardware write protect, hardware protect code, and sequential write/read capability. It is also designed to be a drop-in replacement for any existing Microwire Serial EEPROM applications, as well as a compatible extension to any Serial Peripheral Interface (SPI) application. It is an ideal solution for adding non-volatile memory to new and existing designs.