The AT28C256 is a high-performance electrically erasable and programmable read-only memory. The 256K memory consists of 8 bits of 32,768 words. Manufactured using Atmel's advanced non-volatile CMOS technology, the device provides 150ns of access time with a power consumption of only 440mw. When the device is deselected, the CMOS standby current is less than 200µA.
Block Diagram
The AT28C256 runs read and write loops like static RAM, with no external components required. The device contains a 64-byte page register, allowing up to 64 bytes to be written simultaneously. During the write cycle, the address and 1 to 64 bytes of data are internally latched, freeing up the address and data bus for other operations. After the start of the write cycle, the device automatically writes data to the latch using an internal control timer.the end of the write cycle can be detected using DATA Polling in I/O7. Once the end of a write cycle is detected, a new read or write access can begin.
Atmel's AT28C256 has additional features to ensure high quality and manufacturability. The device utilizes internal error correction to extend life and improve data retention features. Optional software data protection mechanisms can be used to prevent unintentional writes. The device also includes an additional 64-byte EEPROM for device identification or tracking.
Pin Configurations
