Microchip Technology 25LC256-E/SN

Overview

25LC256-E/SN from Microchip Technology is a 256 Kbit SPI Serial EEPROM with 32,768 × 8-bit organization, 64-byte page size, and 10 MHz max clock frequency. It operates across 2.5–5.5V supply and -40°C to +125°C (Extended temp), featuring hardware write protection via WP pin and STATUS register, self-timed 5 ms write cycles, and 1 million endurance cycles. It serves as nonvolatile configuration storage in automotive engine control units.

For engineers reviewing the 25LC256-E/SN datasheet, 25LC256-E/SN pinout, 25LC256-E/SN application, or 25LC256-E/SN equivalent, key selection criteria include SPI timing compliance at 125°C, block protection granularity (1/4, 1/2, or full array), HOLD pin behavior during interrupt servicing, and SO high-impedance state management in multi-device bus configurations.

Technical Context

The 25LC256-E/SN implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS low for device selection and SCK rising edge for input sampling. Its internal architecture includes a status register with WIP and WEL flags, BP0/BP1 bits for configurable block protection, and a write-enable latch reset on power-up or WRDI.

It supports sequential read with automatic address rollover at 7FFFh, byte/page write with strict page-boundary enforcement (64-byte pages), and HOLD pin suspension of ongoing transfers without sequence restart. The WP pin enables hardware-level protection only when WPEN bit is set, allowing flexible factory programming and field update security.

Key Specifications

Pinout & Package

25LC256-E/SN uses an 8-lead SOIC-Narrow (SN) package per Microchip Drawing C04-057-SN Rev E, with 1.27 mm pitch, 3.90 mm body width, and JEDEC-standard footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with AT25DF256A-SSH-T and BR25L256FJ-WE2, the 25LC256-E/SN uniquely balances automotive-grade temperature range, hardware-based write protection, and drop-in SPI compatibility with legacy PIC and ARM designs - making it optimal for ECU retrofit and industrial controller upgrades where minimal firmware and PCB changes are mandatory.

Availability

25LC256-E/SN is available at Aetrix Electronics and suitable for automotive engine control, industrial PLC configuration, and medical infusion pump design requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 25LC256-E/SN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology Inc. is a leading provider of microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.

The 25LC256-E/SN belongs to Microchip's serial EEPROM product line, designed specifically for robust, low-power, SPI-compatible nonvolatile storage in automotive, industrial, and medical applications demanding AEC-Q100 qualification and long-term data integrity.

FAQ

What is the operating voltage range for the 25LC256-E/SN?

The 25LC256-E/SN operates from 2.5V to 5.5V DC. This wide supply range allows direct integration with both 3.3V and 5V microcontroller systems without external level shifters. At 2.5V, the maximum clock frequency reduces to 3 MHz per AC specifications, while full 10 MHz operation is supported at 4.5–5.5V. The device maintains full functionality-including HOLD, WP, and status register access-across the entire voltage range.

Does the 25LC256-E/SN support page write operations, and what is the page size?

Yes, the 25LC256-E/SN supports page write operations with a fixed 64-byte page size. Up to 64 bytes can be written in a single transaction, provided all addresses fall within the same physical page boundary (e.g., 0x0000–0x003F). Crossing a page boundary causes wraparound to the start of the current page-not the next-so software must validate address alignment before initiating page writes. Each page write completes in ≤5 ms, matching byte-write timing.

How does the HOLD pin function during an active SPI transaction on the 25LC256-E/SN?

The HOLD pin on the 25LC256-E/SN suspends an ongoing SPI transaction without resetting internal state. When pulled low while SCK is low, it places SI, SCK, and SO in high-impedance states and freezes the address pointer and instruction decoder. The host MCU can then service higher-priority interrupts and resume communication by raising HOLD while SCK remains low. SO returns to active drive within 30–160 ns (voltage-dependent) after HOLD goes high.

What write protection mechanisms does the 25LC256-E/SN provide?

The 25LC256-E/SN provides three-tiered write protection: (1) a write-enable latch that must be set via WREN instruction before any write, (2) software-configurable block protection (BP0/BP1 bits) enabling 0%, 25%, 50%, or 100% array lock, and (3) hardware write protection via the WP pin when WPEN bit is set. These layers operate independently-e.g., WP pin low blocks STATUS register writes even if WEL=1 and BP bits permit array access.

Is the 25LC256-E/SN qualified for automotive applications, and what is its temperature rating?

Yes, the 25LC256-E/SN is AEC-Q100 qualified for automotive use and rated for Extended temperature range (-40°C to +125°C). The "E" suffix explicitly denotes this grade, and the "/SN" package confirms the 8-lead SOIC-Narrow variant. Its 1 million endurance cycles, >200-year data retention, and 4 kV ESD rating meet stringent requirements for under-hood and chassis-mounted modules in passenger and commercial vehicles.