25LC256-E/SM

Overview

The Microchip Technology 25LC256-E/SM is a 256 Kbit (32K x 8) Serial Electrically Erasable PROM accessed via an SPI-compatible bus. It operates within a supply voltage range of 2.5V to 5.5V and supports a maximum clock frequency of 10 MHz. The device features a 64-byte page size, self-timed erase/write cycles with a maximum duration of 5 ms, and high reliability including 1,000,000 erase/write cycle endurance and data retention exceeding 200 years. It is housed in an 8-lead SOIC package and supports extended industrial temperature ranges from -40°C to +125°C.

Feature Summary

• Supports block write protection allowing configuration to protect none, one-quarter, one-half, or the entire memory array.
• Includes built-in power-on/off data protection circuitry and a write enable latch to prevent inadvertent writes.
• Features a hold pin that allows suspension of serial communication without resetting the sequence.

Applications

• Microcontroller systems requiring non-volatile storage for calibration parameters or device IDs
• Industrial sensor nodes needing reliable data retention under extreme temperatures
• Low-cost embedded systems utilizing software-simulated SPI interfaces

Procurement Notes

Verify the specific suffix 'E' confirms the extended temperature rating (-40°C to +125°C) and 'SM' indicates the 8-lead SOIC package. Confirm RoHS compliance status as required by your assembly specifications. Ensure the ordering code matches the exact voltage and speed requirements for your target application environment.

Selection Notes

Select this component when an SPI interface is preferred over parallel architectures for space-constrained designs. The 25LC256-E variant is suitable for applications operating beyond standard industrial limits. Consider the 64-byte page write limitation when designing firmware to ensure data integrity across page boundaries.

Part Context

This part belongs to the 25XX256 family of 256 Kbit Serial EEPROMs manufactured by Microchip Technology. It shares functional similarities with the 25AA256 but differs in minimum operating voltage. The family supports multiple packages including PDIP, SOIC, TSSOP, and DFN, providing flexibility for various PCB layout requirements.

Replacement Considerations

The 25LC256-I/SM serves as a direct replacement if the extended temperature range is not required. Other variants within the 25LC256 series may be substituted provided the package type and voltage specifications align with the design constraints.

FAQ

How does the HOLD pin function during operation?

The HOLD pin suspends transmission to the device while in the middle of a serial sequence. Transitions on SI, SCK, and SO are ignored during this state, allowing the host to service higher priority interrupts without retransmitting the sequence.

What happens if a page write crosses a physical boundary?

If a page write command attempts to cross a physical page boundary, the data wraps around to the beginning of the current page instead of being written to the next page. Application software must prevent such operations.