The AT28HC256 is a high-performance Electrically Erasable and Programmable Read Only Memory. Its 256K of memory is organized as 32,768 words by 8 bits. Manufactured with Atmel’s advanced nonvolatile CMOS technology, the AT28HC256 offers access times to 70 ns with power dissipation of just 440 mW. When the AT28HC256 is deselected, the standby current is less than 5 mA.
The AT28HC256 is a 256‑Kbit (32K × 8) Electrically Erasable Programmable Read‑Only Memory (E²PROM) built with Atmel’s high‑performance CMOS technology. It offers fast 70 ns read access, low power consumption, and operates over a wide temperature range for commercial, industrial and military applications.
Key features include a 64‑byte page write buffer, automatic write timing, data‑polling for write‑completion detection, optional software data protection, and an extra 64‑byte EEPROM area for device identification. The device is supplied in various packages (PDIP, PLCC, SOIC, etc.) and supports both CMOS and TTL compatible I/O levels.
| Read Access Time | 70 ns |
|---|---|
| Page Write Cycle Time | 3 ms (typ) / 10 ms (max) |
| Active Current | 80 mA |
| Standby Current | 3 mA |
| Supply Voltage | 5 V ±10 % |
| Data Retention | 10 years |
| Endurance (standard) | 10 K write cycles |
| Industrial Temperature Range | -40 °C to 85 °C |
| Military Temperature Range | -55 °C to 125 °C |
The device provides a fast read access time of 70 ns.
The standby current is 3 mA.
It operates from a single 5 V supply with a ±10 % tolerance.
The standard part endures 10 K write cycles; a high‑endurance option is available for up to 100 K cycles.