25AA256-I/ST

Memory IC Overview

The Microchip Technology 25AA256-I/ST is a 256 Kbit Serial Electrically Erasable PROM featuring a 32,768 x 8-bit organization. It utilizes an SPI-compatible serial bus with SCK, SI, SO, and CS signals for communication. The device supports a maximum clock frequency of 10 MHz and operates within a supply voltage range of 1.8V to 5.5V. It includes self-timed erase and write cycles with a maximum duration of 5 ms. The component is housed in an 8-lead TSSOP package and is rated for industrial temperature operation from -40°C to +85°C.

Memory IC Feature Summary

• Supports block write protection allowing selection of none, one-quarter, one-half, or all array segments.
• Includes built-in power-on/off data protection circuitry and a write enable latch.
• Features a hold pin that pauses serial transmission without resetting the sequence.
• Provides high reliability with specified endurance and long-term data retention.

Memory IC Applications

• Data storage in microcontroller systems via SPI interface
• Configuration parameter storage in embedded devices
• Calibration data retention in industrial instrumentation

Memory IC Procurement Notes

Verify the specific suffix 'I' confirms the industrial temperature range (-40°C to +85°C) and 'ST' denotes the 8-TSSOP package. Confirm the 1.8V minimum operating voltage requirement against system power rails, as this differs from the 2.5V minimum of the 25LC256 variant. Ensure compatibility with the host controller's SPI voltage levels and timing constraints before integration.

Memory IC Selection Notes

Select this part when a low-voltage start capability down to 1.8V is required, distinguishing it from the 25LC256 which requires a minimum of 2.5V. The 25AA256 series is suitable for applications needing standard SPI compatibility with hardware write protection options. Consider the TSSOP package dimensions if board space is constrained compared to larger PDIP or SOIC footprints.

Memory IC Part Context

This component belongs to the 25XX256 family of 256 Kbit Serial EEPROMs manufactured by Microchip Technology. The family shares identical functional specifications and instruction sets, differing primarily in operating voltage ranges and temperature grades. The 25AA256 specifically targets lower voltage applications compared to the 25LC256 counterpart.

Memory IC Replacement Considerations

25LC256-I/ST

Memory IC FAQ

How does the HOLD pin function during serial communication?

The HOLD pin allows the user to pause serial communication without resetting the sequence. When pulled low while SCK is low, the device ignores transitions on SI, SCK, and SO pins until HOLD is released.

What is the mechanism for preventing inadvertent writes?

Writes are prevented by requiring a WREN instruction to set the write enable latch before any write operation. The latch resets automatically after power-up, successful write execution, or WRDI instruction.