25LC640/S

Overview

The Microchip Technology 25LC640 is a 64 Kbit (8192 x 8 bit) Serial Electrically Erasable PROM accessed via an SPI-compatible serial bus. It operates within a voltage range of 2.5V to 5.5V and supports clock frequencies up to 3 MHz at higher voltages or 2 MHz at lower voltages. The device features self-timed erase and write cycles with a maximum duration of 5 ms. It includes block write protection, power-on data protection, and a hold pin for pausing communication. Available in 8-pin PDIP, SOIC, and TSSOP packages, it supports industrial temperature ranges.

Feature Summary

• Supports SPI-compatible serial interface with separate data input and output lines controlled by chip select
• Includes hardware write-protect pin and software-configurable block protection for array segments
• Features built-in power-on/off data protection circuitry and a write enable latch mechanism
• Provides a hold function to pause serial transmission without resetting the sequence

Applications

• Microcontroller system data storage
• Configuration parameter retention
• Calibration value storage
• Device identification information logging

Procurement Notes

Verify the specific suffix indicates the correct package type and temperature grade. Confirm the voltage variant matches the system requirements, as different suffixes correspond to distinct operating voltage ranges and clock speeds. Ensure the ordering code aligns with the required industrial temperature specifications and physical footprint constraints.

Selection Notes

Select based on the required supply voltage range and maximum clock frequency. Verify the necessary package style against board layout constraints. Consider the write protection requirements to determine if hardware WP pin usage or software block protection is preferred. Check temperature ratings to ensure compatibility with the operational environment.

Part Context

The 25LC640 belongs to the 25XX640 family of 64 Kbit serial EEPROMs from Microchip Technology. It shares functional similarities with the 25AA640 but differs in operating voltage and speed specifications. This component is designed for non-volatile data storage applications requiring simple serial interface connectivity.

Replacement Considerations

Datasheet notes that this part is not recommended for new designs; the 25LC640A is suggested as a replacement. Verify electrical characteristics and pinout compatibility when substituting with other 64 Kbit SPI EEPROMs.