Microchip Technology AT28C256 256K EEPROM Memory

Microchip AT28C256 256K EEPROM Memory devices are high-performance, Electrically Erasable, and Programmable Read-only Memory (EEPROM). The EEPROM 256K of memory is organized as 32,768 words by 8-bits. These devices are manufactured with Atmel's advanced non-volatile CMOS technology, offering 150ns access time with 440mW power dissipation. The AT28C256 memory devices are accessed like static RAM for reading or writing cycles without needing external components. These AT28C256 devices contain a 64-byte page register to allow writing up to 64 bytes. The EEPROM devices utilize an internal error correction for extended endurance and improved data retention. 

An optional software data protection mechanism is available to guard against unplanned writes. These AT28C256 devices also include 64 bytes of EEPROM for device identification or tracking.


  • Fast read access time of 150ns
  • Automatic page write operation
    • Internal address and data latches for 64 bytes
    • Internal control timer
  • Fast write cycle times:
    • Page write cycle time of 3ms or 10ms (maximum)
    • 1 to 64-bytes page write operation
  • Hardware and software data protection
  • DATA polling for end of write detection
  • High-reliability CMOS technology
    • 104 or 105 cycles of endurance
    • 10years data retention
  • CMOS and TTL compatible inputs and outputs
  • JEDEC approved byte-wide pinout
  • Full military and industrial temperature ranges
  • Green (Pb/Halide-free) packaging option


  • Single 5V ±10% supply
  • Low power dissipation
    • 50mA active current
    • 200µA CMOS standby current
  • 2V (minimum) Input High Voltage (VIH)
  • 2.4V (minimum) Output High Voltage (VOH)

Block Diagram

Block Diagram - Microchip Technology AT28C256 256K EEPROM Memory
Published: 2018-01-04 | Updated: 2022-09-23