AT24C256B is a low-power, low-voltage 262,144-bit serial electrically erasable and programmable read-only memory (EEPROM), organized as 32,768 words of 8 bits each. The device's cascadable feature allows up to eight devices to share a common two-wire bus. The device is optimized for use in many industrial and commercial applications where low-power and low-voltage operation are essential.
The AT24C256B is a 256‑kilobit (32,768 × 8) serial EEPROM offered by Atmel in various 8‑lead packages such as PDIP, SOIC, Ultra‑Thin SAP, TSSOP, and 8‑ball BGA. It operates from 1.8 V to 5.5 V, supports up to eight devices on a common two‑wire I²C bus, and provides high reliability with one‑million write‑cycle endurance and 40‑year data retention.
This datasheet provides the full feature list, pin descriptions, absolute maximum ratings, DC and AC electrical characteristics, memory organization, timing diagrams, and software reset procedure. Engineers can use the tables and figures to design circuits, verify timing, and ensure proper operation in industrial and commercial applications.
| Memory size | 256 Kbits (32,768 × 8) |
|---|---|
| Supply voltage | 1.8 V – 5.5 V |
| Write cycle time | 5 ms max |
| Endurance | 1 million write cycles |
| Data retention | 40 years |
| Page size | 64 bytes |
| Number of pages | 512 |
| Maximum clock frequency | 1 MHz (5 V) / 400 kHz (1.8 V) |
The device operates from 1.8 V up to 5.5 V.
It is rated for up to one million write cycles.
Up to eight AT24C256B devices can be cascaded on a common bus.
The EEPROM supports up to 1 MHz at 5 V (or 400 kHz at 1.8 V).