25LC640AT-I/SN

Overview

The Microchip Technology 25LC640AT-I/SN 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 2.5V to 5.5V and supports clock frequencies up to 10 MHz at 5.5V. The device features low-power CMOS technology with standby current as low as 1 µA. It includes hardware write protection, self-timed erase/write cycles of 5 ms maximum, and high reliability with 1,000,000 erase/write cycle endurance and data retention exceeding 200 years.

Feature Summary

• Supports serial communication via SPI interface with hold functionality for pausing transmission without resetting the sequence.
• Includes built-in write protection mechanisms such as power-on/off data protection, write enable latch, and dedicated write-protect pin.
• Features block write protection allowing selection of none, 1/4, 1/2, or all array segments for security.

Applications

• Microcontroller systems requiring non-volatile data storage
• Industrial control applications
• Automotive electronics

Procurement Notes

Verify that the ordering suffix 'SN' corresponds to the SOIC package and 'I' indicates the industrial temperature range (-40°C to +85°C). Confirm the 'T' suffix aligns with the required tape-and-reel packaging format. Ensure compatibility with the 2.5V to 5.5V supply voltage requirements for your specific circuit design.

Selection Notes

Select this component when an SPI-compatible EEPROM with 64-Kbit capacity is needed. It is suitable for designs requiring low standby power and robust data retention. Consider the 32-byte page size for write operations and ensure the system supports the required SPI clock speeds based on the operating voltage.

Part Context

This part belongs to the 25LC640A series of 64-Kbit Serial EEPROMs from Microchip Technology. It shares functional similarities with the 25AA640A but differs in minimum operating voltage. The series is designed for direct interfacing with popular microcontroller families, including PIC microcontrollers, offering a reliable solution for small-scale data logging and configuration storage.

Replacement Considerations

The 25LC640A is the base model for this series. Verify if the 25LC640 variant without the 'A' suffix is available, though the datasheet primarily references the 'A' version. Check for alternative packages like MSOP or TSSOP if physical space constraints differ, ensuring the electrical characteristics remain compatible.

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, it places inputs in a high-impedance state. Communication resumes when HOLD is brought high while SCK is low.

What is the purpose of the WPEN bit in the STATUS register?

The WPEN bit enables or disables the hardware write-protect function of the WP pin. When WPEN is high and WP is low, writing to the nonvolatile bits in the STATUS register is disabled.