25CS640T-E/Q4B

Overview

The Microchip Technology 25CS640T-E/Q4B is a 64-Kbit (8,192 x 8 bit) SPI Serial EEPROM housed in an 8-pad UDFN package. It operates within a voltage range of 1.8V to 5.5V and supports clock frequencies up to 20 MHz at VCC ≥ 4.5V. The device features built-in Error Correction Code (ECC) logic, a Security Register with a preprogrammed 128-bit serial number, and Enhanced Write Protection modes. Designed for industrial applications, it functions across an extended temperature range of -40°C to +125°C.

Feature Summary

• Built-in ECC logic corrects single-bit errors during read operations to enhance data reliability.
• Security Register includes a factory-programmed 128-bit unique serial number and a user-programmable lockable ID page.
• Enhanced Write Protection mode allows independent configuration of memory partitions with unique protection behaviors.
• Programmable Undervoltage Lockout Detection circuit inhibits write sequences during brown-out events.

Applications

• Automotive systems requiring AEC-Q100 qualified nonvolatile memory
• Industrial control systems needing reliable data storage
• Consumer electronics utilizing high-speed SPI interfaces

Procurement Notes

Verify the specific suffix 'E' confirms the Extended temperature rating (-40°C to +125°C) and minimum operating voltage of 1.8V. Confirm the 'Q4B' designation corresponds to the 8-pad UDFN package type. Ensure compatibility with the host controller's SPI voltage levels and clock speed requirements before integration.

Selection Notes

Select this component when application demands exceed the capabilities of standard EEPROMs through integrated error correction. The Extended temperature grade is suitable for harsh environments where ambient temperatures reach +125°C. The inclusion of a unique serial number simplifies manufacturing serialization processes compared to devices lacking this feature.

Part Context

This part belongs to the 25CS640 family of SPI Serial EEPROMs from Microchip Technology. It is backward compatible with legacy devices such as the 25AA640A and AT25C640B. The T/E/Q4B suffix indicates tape-and-reel packaging, Extended temperature operation, and the specific UDFN-8 physical footprint.

Replacement Considerations

Direct replacements include other 25CS640 variants with different packages or temperature grades, such as 25CS640T-I/Q4B for Industrial temperature or 25CS640T-E/ST for TSSOP packaging. Verify pinout and electrical specifications match before substitution.