25AA256XT-I/ST

Memory IC Overview

The Microchip Technology 25AA256XT-I/ST is a 256 Kbit Serial Electrically Erasable PROM featuring a 32,768 x 8-bit organization. It interfaces via an SPI-compatible serial bus with a maximum clock frequency of 10 MHz. The device operates within a supply voltage range of 1.8 V to 5.5 V and supports industrial temperature ranges from -40°C to +85°C. It utilizes low-power CMOS technology with standby current of 1 µA and includes self-timed erase/write cycles of 5 ms max. The component is housed in an 8-lead TSSOP package.

Memory IC Feature Summary

• Supports block write protection for none, 1/4, 1/2, or all of the memory array.
• Includes built-in power-on/off data protection circuitry and a write enable latch.
• Features a hold pin to pause serial communication without resetting the sequence.
• Provides high reliability with over 1,000,000 erase/write cycles and greater than 200 years data retention.

Memory IC Applications

• Microcontroller systems requiring non-volatile data storage
• Industrial control applications operating in wide temperature ranges
• Embedded systems utilizing SPI bus communication

Memory IC Procurement Notes

Verify that the ordering suffix 'XT' corresponds to the tape and reel packaging format as specified by the manufacturer. Confirm the 'I' designation indicates the industrial temperature grade (-40°C to +85°C). Ensure the voltage range requirements align with the 1.8V to 5.5V specification before integration into the design.

Memory IC Selection Notes

Select this component when a 256 Kbit capacity is required with low-voltage operation starting at 1.8 V. The industrial temperature rating makes it suitable for environments exceeding standard commercial limits. The TSSOP package offers a compact surface-mount solution for space-constrained designs.

Memory IC Part Context

This part belongs to the 25AA256 family of SPI Bus Serial EEPROMs manufactured by Microchip Technology. It shares functional similarities with the 25LC256 but differs in minimum operating voltage. The device is designed for direct interface with popular microcontroller families supporting the SPI protocol.

Memory IC Replacement Considerations

The 25LC256 is a compatible alternative within the same family, though it requires a minimum supply voltage of 2.5 V compared to the 1.8 V minimum of the 25AA256. Verify voltage compatibility before substitution.

Memory IC FAQ

How does the HOLD pin function during serial communication?

The HOLD pin allows the host to pause transmission to the device without resetting the serial sequence. Transitions on SI, SCK, and SO are ignored while held low, and communication resumes when the pin is brought high.

What is the mechanism for preventing inadvertent writes?

Writes are prevented by a write enable latch that must be set via the WREN instruction. The latch resets automatically after power-up, successful write execution, or upon issuing the WRDI instruction.