25AA640AT-E/MNY

Memory IC Overview

The Microchip Technology 25AA640AT-E/MNY is a 64-Kbit (8192 x 8-bit) Serial Electrically Erasable PROM accessed via an SPI-compatible bus. It operates within a supply voltage range of 1.8V to 5.5V and supports clock frequencies up to 10 MHz at higher voltages. The device features a 32-byte page size, self-timed erase/write cycles with a maximum duration of 5 ms, and high reliability including 1,000,000 write/erase cycles and data retention exceeding 200 years. It is qualified under the AEC-Q100 automotive standard and supports an extended temperature range from -40°C to +125°C.

Memory IC Feature Summary

• Supports block-level write protection for none, one-quarter, one-half, or all memory array segments.
• Includes built-in power-on/off data protection circuitry and a dedicated write-protect pin.
• Allows serial communication suspension via a hold pin without resetting the sequence.

Memory IC Applications

• Automotive electronic systems requiring AEC-Q100 qualification
• Microcontroller-based data logging applications
• Configuration storage in industrial embedded devices

Memory IC Procurement Notes

Verify that the specific ordering suffix matches the required package type and temperature grade. Confirm the 'T' designation indicates tape-and-reel packaging if reel handling is necessary for assembly. Ensure the voltage range aligns with system requirements, as this variant supports low-voltage operation down to 1.8V.

Memory IC Selection Notes

Select this component when an SPI interface is preferred over I2C for faster data throughput. Choose the extended temperature grade (-E) for environments exceeding standard industrial limits. Consider the 32-byte page size constraints for write operations to optimize software efficiency and prevent data wrap-around errors.

Memory IC Part Context

This part belongs to the 25AA640A/25LC640A family of 64-Kbit SPI EEPROMs. The 'AA' series denotes support for lower voltage operation starting at 1.8V, distinguishing it from the 'LC' series which typically requires a minimum of 2.5V. Both share identical functional specifications and pinouts.

Memory IC Replacement Considerations

The 25LC640A is functionally equivalent but has a different voltage specification. Verify voltage compatibility before substitution. Other packages in the same family, such as MSOP or TSSOP, are pin-compatible but require checking physical footprint constraints.

Memory IC FAQ

How does the HOLD pin affect ongoing serial communication?

Pulling the HOLD pin low pauses serial communication while keeping the device selected. Transitions on SI, SCK, and SO are ignored until the pin is released, allowing the host to service interrupts without retransmitting the sequence.

What happens if a page write crosses a physical page boundary?

If a page write attempts to cross a boundary, the data wraps around to the beginning of the current page, overwriting existing data instead of proceeding to the next page. Software must manage addresses to prevent this.