The AT24C128/256 are a series of serial electrically erasable and programmable read only memory (EEPROM) for automotive applications, providing 131,072/262,144 bits, organized as 16,384/32,768 words of 8 bits each. The device's cascadable feature allows up to 4 devices to share a common Two-wire bus. The device is optimized for use in many automotive applications where low power and low voltage operation are essential. The AT24C128 is available in space-saving 8-lead JEDEC SOIC and 8-lead TSSOP packages. The AT24C256 is available in a space-saving 8-lead JEDEC SOIC package. In addition, the entire family is available in 2.7V (2.7V to 5.5V) version.
This document describes the AT24C128 and AT24C256 serial EEPROM devices, including their low‑voltage and standard‑voltage operation, 2‑wire I²C interface, and memory organization of 16,384 × 8 and 32,768 × 8 bits. Features such as write‑protect, page‑write mode, and high reliability (40‑year data retention) are highlighted.
Technical details cover absolute maximum ratings, DC and AC characteristics, pin functions, timing diagrams, device addressing, and package dimensions. The datasheet also includes revision history and mechanical drawing information for the 8‑lead SOIC and TSSOP packages.
| Supply Voltage | 2.7 V – 5.5 V |
|---|---|
| Input Low Level (VIL) | -0.6 V |
| Input High Level (VIH) | 0.7 × VCC |
| Clock Frequency (SCL) | 400 kHz |
| Write Cycle Time | 5 ms |
| Data Retention | 40 years |
| Operating Temperature Range | -40 °C to +125 °C |
| SDA Input Capacitance | 8 pF |
| SCL Input Capacitance | 6 pF |
The devices support a maximum clock frequency of 400 kHz.
Up to four devices can share a common two‑wire bus.
The write cycle time is specified as 5 ms.
Data retention is rated for 40 years.