25AA640AX-I/ST

Memory IC Overview

The Microchip Technology 25AA640AX-I/ST is a 64-Kbit (8192 x 8-bit) Serial Electrically Erasable PROM accessed via an SPI-compatible bus. It operates within a voltage range of 1.8V to 5.5V and supports a maximum clock frequency of 10 MHz at higher voltages. The device features a 32-byte page size, self-timed write cycles up to 5 ms, and industrial temperature ratings from -40°C to +85°C. It utilizes low-power CMOS technology with standby current as low as 1 µA.

Memory IC Feature Summary

• Supports serial communication through standard SPI signals including clock, data in, data out, and chip select inputs.
• Includes hardware write protection mechanisms controlled by the WP pin and STATUS register bits.
• Features a HOLD input to pause serial transmission without resetting the communication sequence.
• Provides block-level write protection allowing selection of none, one-quarter, one-half, or all array segments.

Memory IC Applications

• Data storage for configuration parameters in microcontroller systems
• Logging operational history or event records in embedded devices
• Storing calibration constants and device identifiers

Memory IC Procurement Notes

Verify that the ordering suffix 'I' corresponds to the Industrial temperature range (-40°C to +85°C) and 'ST' indicates the TSSOP package. Confirm the 'X' suffix aligns with specific marking or rotation requirements if critical for assembly. Ensure supply voltage levels match the 1.8V to 5.5V specification for reliable operation.

Memory IC Selection Notes

Select this component when a non-volatile memory solution requires SPI interface compatibility with low pin count. It is suitable for applications needing moderate endurance and long data retention. Consider the 32-byte page write limitation for software design. Verify that the operating voltage environment falls within the specified 1.8V to 5.5V range.

Memory IC Part Context

This part belongs to the 25AA640A/25LC640A family of 64-Kbit SPI EEPROMs. The 'AA' designation typically implies a wider voltage range starting at 1.8V compared to the 'LC' variant which starts at 2.5V. The device shares functional architecture with other members of the 25XX640A series but differs in electrical specifications and temperature grades.

Memory IC Replacement Considerations

Public confirmed substitute part numbers include 25AA640A-I/ST and 25LC640A-I/ST. Verify voltage range compatibility when substituting with the LC variant. Other package options like MSOP or SOIC are available within the same family.