AT28HC256

The AT28HC256 is a high-performance Electrically Erasable and ProgrammableRead Only Memory. Its 256K of memory is organized as 32,768 words by 8 bits. Man-ufactured with Atmel's advanced nonvolatile CMOS technology, the AT28HC256offers access times to 70 ns with power dissipation of just440 mW. When the AT28HC256 is deselected, the standbycurrent is less than 5 mA.

The AT28HC256 is accessed like a Static RAM for the reador write cycle without the need for external components.The device contains a 64-byte page register to allow writingof up to 64 bytes simultaneously. During a write cycle, theaddress and 1 to 64 bytes of data are internally latched,freeing the addresses and data bus for other operations.
Following the initiation of a write cycle, the device will auto-matically write the latched data using an internal controltimer. The end of a write cycle can be detected by DATA polling of I/O₇ . Once the end of a write cycle has been
detected a new access for a read or write can begin.

Atmel's 28HC256 has additional features to ensure highquality and manufacturability. The device utilizes internal error correction for extended endurance and improved dataretention characteristics. An optional software data protec-tion mechanism is available to guard against inadvertentwrites. The device also includes an extra 64 bytes ofEEPROM for device identification or tracking.