EEPROMs

EEPROM stands for electrically erasable programmable read-only memory. It is a non-volatile memory that retains data when power is removed, making it suitable for storing configuration data, calibration constants, serial numbers, and other small data that must survive resets or power loss.

Most EEPROMs are byte-addressable and can read or write individual bytes, though some devices use page or sector operations for bulk updates. They are typically implemented with floating-gate transistors, and data are stored as charge on the floating gate. Erasure is accomplished electrically by tunneling mechanisms, after which programming places charge to represent bits. Modern devices may support interfaces such as I2C or SPI, and exist in parallel configurations too.

Endurance and retention: EEPROM cells are rated for roughly 100 thousand to one million write/erase cycles, with data retention commonly specified for ten to twenty years at room temperature. Densities range from a few kilobits to a few megabits, depending on the device and process technology.

Relationship to flash memory: like flash, EEPROM is non-volatile, but traditional EEPROMs permit in-place byte-level updates without a full erasure of a large block, whereas flash usually requires erasing larger blocks before programming. Because of this, EEPROM is used for small amounts of stored data, while flash dominates bulk storage. Many microcontrollers provide an emulated EEPROM in flash to host similar functionality, implemented in software.

Variants and applications: EEPROM is used in automotive, industrial, and consumer electronics, often featuring extended temperature ranges for reliability. Packaging includes DIP, SOIC, and other small-outline formats to suit embedded designs.