25AA640AT-E/ST

Memory IC Overview

The Microchip Technology 25AA640AT-E/ST is a 64-Kbit serial Electrically Erasable PROM accessed via an SPI-compatible bus. It features an 8192 x 8-bit organization with a 32-byte page size. The device supports a maximum clock frequency of 10 MHz at VCC voltages between 4.5V and 5.5V, reducing to 5 MHz at 2.5V–4.5V and 3 MHz at 1.8V–2.5V. Operating voltage ranges from 1.8V to 5.5V. It is housed in an 8-lead TSSOP package and qualified for the Extended temperature range (-40°C to +125°C) under AEC-Q100 standards.

Memory IC Feature Summary

• Supports hardware write protection through a dedicated pin and nonvolatile STATUS register bits.
• Includes a HOLD input to pause serial communication without resetting the sequence.
• Features built-in power-on/off data protection circuitry and a write enable latch.

Memory IC Applications

• Automotive electronic systems requiring AEC-Q100 qualification
• Microcontroller-based data logging applications
• Industrial control systems operating in extended temperature environments

Memory IC Procurement Notes

Verify that the specific suffix 'E' confirms the Extended temperature rating (-40°C to +125°C) rather than Industrial. Confirm the 'T' indicates tape-and-reel packaging if required for automated assembly. Ensure the 'ST' designation matches the 8-lead TSSOP package footprint. Cross-reference the datasheet revision DS20001830G for accurate electrical characteristics.

Memory IC Selection Notes

Select this component when low standby current and high endurance are required for automotive or industrial use. The 1.8V minimum supply voltage allows compatibility with low-voltage logic families. The 32-byte page size optimizes write efficiency compared to byte-only programming. Verify system voltage levels against the frequency-dependent timing specifications.

Memory IC Part Context

This part belongs to the 25AA640A/25LC640A family of 64K SPI Bus Serial EEPROMs. While electrically similar to the 25LC640A, the 25AA640A variant uniquely supports a lower minimum supply voltage of 1.8V. Both share identical instruction sets, pinouts, and physical packages, differing primarily in their voltage tolerance profiles.

Memory IC Replacement Considerations

The 25LC640AT-E/ST serves as a direct functional substitute within the same package and temperature range. Note that the 25LC640A requires a minimum supply voltage of 2.5V, whereas the 25AA640A operates down to 1.8V. Other family members like the 25AA640I/ST offer the same voltage range but with a restricted Industrial temperature rating.