25LC256T-E/SM

Overview

The Microchip Technology 25LC256T-E/SM is a 256 Kbit (32K x 8) Serial Electrically Erasable PROM accessed via an SPI-compatible bus. It operates within a voltage range of 2.5V to 5.5V and supports clock frequencies up to 10 MHz at 5.5V. The device features a 64-byte page size, self-timed write cycles with a maximum duration of 5 ms, and high reliability including 1,000,000 erase/write cycles and data retention exceeding 200 years. It is housed in an 8-lead SOIJ package and supports extended industrial temperature ranges from -40°C to +125°C.

Feature Summary

• Supports sequential read operations and page writes up to 64 bytes within a single physical page boundary.
• Includes built-in write protection mechanisms such as a write enable latch, power-on/off data protection, and programmable block protection for none, 1/4, 1/2, or all of the array.
• Features a HOLD input pin that allows suspension of serial communication without resetting the sequence, facilitating higher priority interrupt servicing.

Applications

• Data storage for calibration parameters and device identification in microcontroller systems
• Configuration memory for industrial sensor nodes and embedded control boards
• Non-volatile storage for user settings in low-power CMOS applications

Procurement Notes

Verify the specific suffix 'E' confirms the extended temperature range (-40°C to +125°C) and 'SM' denotes the 8-SOIJ package. Confirm RoHS compliance status and ensure the ordering quantity matches the manufacturer's standard packaging specifications. Cross-reference the datasheet revision to ensure compatibility with current design requirements.

Selection Notes

Select this component when SPI interface compatibility is required alongside non-volatile storage needs. Ensure the system voltage falls within the 2.5V to 5.5V operating range. Consider the 64-byte page write limitation and the need for software management of page boundaries to prevent data wrap-around during write operations.

Part Context

This part belongs to the 25XX256 family of Serial EEPROMs, sharing functional similarities with the 25AA256 variant which offers a wider voltage range starting at 1.8V. Both devices utilize the same SPI protocol and pinout but differ in supply voltage specifications and temperature grades. The 25LC256 series is designed for general-purpose industrial applications requiring robust data retention.

Replacement Considerations

The 25LC256I/SM is a compatible alternative offering the same functionality but restricted to the Industrial temperature range (-40°C to +85°C). Verify that the reduced temperature range meets the operational requirements of the target application before substitution.

FAQ

How does the device handle page write operations that cross physical page boundaries?

If a page write command attempts to write across a physical page boundary, the data wraps around to the beginning of the current page, overwriting previously stored data, rather than proceeding to the next page.

What is the function of the HOLD pin during serial communication?

The HOLD pin suspends transmission to the device while in the middle of a serial sequence without resetting the sequence. Transitions on SI, SCK, and SO pins are ignored while HOLD is asserted.