25LC040X-I/ST

Overview

The Microchip Technology 25LC040X-I/ST is a 4 Kbit (512 x 8-bit) serial Electrically Erasable PROM. It operates within a voltage range of 2.5V to 5.5V and supports a maximum clock frequency of 2 MHz. The device utilizes an SPI-compatible serial bus with SCK, SI, SO, CS, HOLD, and WP pins. It features low-power CMOS technology with typical standby current of 500 nA. Endurance is rated at 1 million cycles, with data retention exceeding 200 years. The component is housed in an 8-lead TSSOP package and supports the Industrial temperature range of -40°C to +85°C.

Feature Summary

• Supports sequential read operations and self-timed erase/write cycles via SPI interface
• Includes hardware write protection through the WP pin and software block protection for array segments
• Features built-in power-on/off data protection circuitry and a write enable latch
• Allows communication pausing via the HOLD pin without resetting the serial sequence

Applications

• Configuration storage in microcontroller systems
• Calibration parameter persistence
• Log data buffering
• Device identification and security codes

Procurement Notes

Verify that the 'X' suffix indicates the alternate pinout configuration specific to the ST package, as this differs from standard pin assignments. Confirm the 'I' designation matches the required industrial temperature range (-40°C to +85°C). Ensure the design accounts for the 2.5V minimum operating voltage. Check for updated datasheets as this family is noted as not recommended for new designs.

Selection Notes

Select this part when a 4 Kbit capacity is sufficient and the application requires the specific alternate pinout layout of the 25LC040X variant. Verify compatibility with the host controller's SPI timing requirements at 2 MHz. Consider the 16-byte page write limitation which requires careful address management to prevent unwanted page rollover during writes.

Part Context

This component belongs to the 25XX040 family, which includes the 25AA040, 25LC040, and 25C040 variants. The 25LC040 series specifically targets applications requiring a 2.5V to 5.5V supply range. The 'X' suffix denotes a unique pinout arrangement available only in the TSSOP package, distinguishing it from the standard 25LC040 pin configuration.

Replacement Considerations

Microchip recommends using the 25LC040A or 25AA040A for new designs. These newer variants offer improved specifications but may have different electrical characteristics or pinouts. Direct substitution requires verification of voltage ranges, timing parameters, and physical package compatibility.