25LC640X-I/ST

Overview

The Microchip Technology 25LC640X-I/ST 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 industrial temperature ranges (-40°C to +85°C). Electrical characteristics include a typical read current of 500 μA and standby current of 500 nA. Maximum clock frequency varies by voltage: up to 3 MHz at 4.5V–5.5V, 2 MHz at 2.5V–5.5V, and 1 MHz at 1.8V–5.5V. It features self-timed erase/write cycles with a maximum write cycle time of 5 ms.

Feature Summary

• Supports block write protection allowing selection of none, 1/4, 1/2, or all array segments.
• Includes built-in power on/off data protection circuitry and a write enable latch.
• Provides hardware write protection via the WP pin in conjunction with the STATUS register WPEN bit.
• Features a HOLD input to pause serial transmission without resetting the sequence.

Applications

• Microcontroller systems requiring non-volatile data storage
• Industrial control applications within specified temperature ranges
• Embedded devices utilizing SPI interfaces

Procurement Notes

Verify that the specific ordering suffix matches the required package type and voltage range. Confirm the 'I' designation corresponds to the industrial temperature range requirements. Ensure compatibility with the system's SPI voltage levels before procurement.

Selection Notes

Select this component for designs requiring 64 Kbit capacity with SPI interface. Consider the 25LC640A series as the recommended replacement for new designs. Verify voltage supply constraints against the supported frequency specifications.

Part Context

This part belongs to the 25AA640/25LC640 family of 64 Kbit Serial EEPROMs. The 'X' indicates a generic placeholder for various package options like TSSOP. The 'I' suffix denotes the industrial temperature grade. This generation is noted as not recommended for new designs.

Replacement Considerations

Public confirmed substitute part numbers include 25LC640A-I/ST.

FAQ

How does the HOLD pin function during operation?

The HOLD pin suspends transmission when pulled low while SCK is low, ignoring transitions on other inputs except Chip Select until released.

What determines the maximum clock frequency?

The maximum clock frequency depends on the VCC supply voltage, ranging from 1 MHz at lower voltages to 3 MHz at higher voltages.