The 25AA640/25LC640 is a 64Kbit EEPROM produced by Microchip Technology Inc. It has low power consumption, high reliability and data retention for more than 200 years.
The 25AA640 and 25LC640 are 64‑Kbit (8192 × 8) Serial EEPROM devices that communicate via a standard SPI interface. They are available in 8‑pin PDIP, SOIC, and TSSOP packages and operate over a wide voltage range (1.8‑5.5 V for 25AA640, 2.5‑5.5 V for 25LC640). The devices support industrial (‑40 °C to +85 °C) and automotive (‑40 °C to +125 °C) temperature grades.
Key features include a 32‑byte page size, a maximum write cycle time of 5 ms, low standby current (500 nA), and built‑in write protection. Timing diagrams, pin descriptions, and instruction sets are provided for read, write, and hold operations, along with specifications such as data retention (>200 years) and ESD protection (>4000 V).
| Memory organization | 8192 × 8 bits |
|---|---|
| Page size | 32 bytes |
| Write cycle time | 5 ms max |
| Write current | 3 mA typical |
| Read current | 500 µA typical |
| Standby current | 500 nA typical |
| Operating temperature (Industrial) | -40 °C to +85 °C |
| Operating temperature (Automotive) | -40 °C to +125 °C |
| Package types | PDIP, SOIC, TSSOP |
| Data retention | >200 years |
| ESD protection | >4000 V |
| Supply voltage (25AA640) | 1.8 V – 5.5 V |
| Supply voltage (25LC640) | 2.5 V – 5.5 V |
The device specifies a maximum write cycle time of 5 ms.
Up to 32 bytes can be written in one page write.
The 25LC640 operates from 2.5 V to 5.5 V.
The HOLD pin pauses serial communication while keeping the device selected; it must be high when not in use.