25LC640AT-H/ST16KVAO

Overview

The Microchip Technology 25LC640AT-H/ST16KVAO is a mid-density serial electrically erasable programmable read-only memory (EEPROM) with a storage capacity of 64 Kbit, organized as 8,192 x 8 bits. It utilizes a Serial Peripheral Interface (SPI) compatible bus architecture for communication. The device supports extended temperature operation ranging from -40°C to +150°C and operates within a supply voltage range of 2.5V to 5.5V. Maximum clock frequency is 5 MHz at voltages between 4.5V and 5.5V, and 3 MHz at voltages between 2.5V and 4.5V. It features a page size of 32 bytes and is housed in an 8-lead SOIC package.

Feature Summary

• Supports block-level write protection allowing configuration to protect none, one-quarter, one-half, or the entire memory array via status register settings.
• Includes built-in power-on/off data protection circuitry and a write enable latch to prevent inadvertent writes during system transitions.
• Features a hold pin that allows suspension of serial communication sequences without resetting the internal address pointer.

Applications

• Embedded systems requiring non-volatile data storage under high ambient temperatures
• Industrial control applications utilizing SPI-compatible microcontrollers
• Automotive electronics components subject to AEC-Q100 reliability standards

Procurement Notes

Verify the specific suffix 'H' confirms the extended temperature grade (-40°C to +150°C) and 'ST16KVAO' indicates automotive qualification. Confirm the package type matches the required 8-lead SOIC footprint. Ensure the design accounts for the maximum clock speed limitations relative to the operating supply voltage.

Selection Notes

Select this component when application environments exceed standard industrial temperature limits up to 150°C. The device offers hardware write protection capabilities suitable for safety-critical configurations. Verify that the host controller supports the required SPI modes and can manage the write cycle timing constraints defined in the datasheet.

Part Context

This part belongs to the 25LCXXX family of mid-density serial EEPROMs manufactured by Microchip Technology. The family shares common instruction sets and functional architectures across various densities ranging from 8 Kbit to 256 Kbit. The specific designation denotes the 64 Kbit variant optimized for high-temperature automotive and industrial deployments.

Replacement Considerations

Compatible substitutes include other 25LC640A variants with different temperature grades or packages, such as 25LC640A-I/SN. Cross-referencing with the 25AA640A series may be possible if voltage requirements align, though electrical characteristics should be verified against the source datasheet.

FAQ

How does the HOLD pin function 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 held low, allowing the host to service higher priority interrupts.

What determines the maximum clock frequency for this device?

The maximum clock frequency depends on the supply voltage. It is 5 MHz when VCC is between 4.5V and 5.5V, and reduces to 3 MHz when VCC is between 2.5V and 4.5V.