25LC640T-E/SN

Overview

The Microchip Technology 25LC640T-E/SN is a 64 Kbit (8192 x 8 bit) Serial Electrically Erasable PROM. It utilizes an SPI-compatible serial bus for communication, requiring SCK, SI, SO, and CS signals. The device supports a maximum clock frequency of 3 MHz at supply voltages between 4.5 V and 5.5 V. It operates within an extended industrial temperature range of -40 °C to +125 °C. The component is housed in an 8-lead TSSOP package.

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 with a write enable latch mechanism.
• Features a hold pin that suspends transmission mid-sequence without resetting the serial operation.

Applications

• Microcontroller system data storage
• Configuration parameter retention
• Calibration value storage

Procurement Notes

Verify the specific suffix 'E' indicates the automotive-grade temperature range (-40°C to +125°C) and voltage requirements (4.5V to 5.5V). Confirm the 'SN' designation corresponds to the 8-lead TSSOP package. Ensure the datasheet DS21223H is referenced for accurate electrical characteristics and timing parameters before finalizing procurement specifications.

Selection Notes

Select this component when an SPI interface is required for non-volatile memory applications needing extended temperature resilience. The automotive grade ensures reliability under higher thermal stress compared to standard industrial versions. Verify that the minimum operating voltage of 4.5 V aligns with the target system's power supply rails.

Part Context

This part belongs to the 25LC640 family of serial EEPROMs manufactured by Microchip Technology. It shares architectural similarities with the 25AA640 but differs in voltage tolerance and temperature ratings. The device provides a cost-effective solution for storing small amounts of persistent data in embedded systems requiring simple serial connectivity.

Replacement Considerations

The 25LC640A series serves as the recommended successor. Direct replacements include the 25LC640AT-E/ST for TSSOP packages or the 25LC640AT-I/ST for industrial grades. Verify pin compatibility and updated electrical specifications when transitioning from the legacy 25LC640 model.

FAQ

How does the HOLD pin function during serial communication?

The HOLD pin allows the host to pause serial communication without resetting the sequence. When pulled low while SCK is low, inputs are ignored until the pin is raised high again.

What is the purpose of the Write Enable Latch?

The Write Enable Latch must be set via the WREN instruction before any write operations can occur. It resets automatically after power-up or upon completion of a write cycle to prevent inadvertent writes.