Microchip Technology 25LC256T-E/MF

Overview

25LC256T-E/MF from Microchip Technology Inc. is a 256 Kbit (32,768 × 8) SPI serial EEPROM with 64-byte page write capability, 10 MHz max clock frequency at 4.5–5.5 V, and industrial-grade operation from −40°C to +85°C. It features hardware write protection via WP pin and STATUS register, self-timed 5 ms write cycles, and 1 μA standby current - deployed in embedded control modules for firmware storage and calibration data retention.

For engineers reviewing the 25LC256T-E/MF datasheet, 25LC256T-E/MF pinout, 25LC256T-E/MF application, or 25LC256T-E/MF equivalent, this page delivers verified electrical specs, SPI timing constraints, HOLD/CS interaction behavior, block protection mapping, and real-world use cases in automotive body controllers and industrial sensor nodes.

Technical Context

The 25LC256T-E/MF implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (data in) and SO (data out) lines, requiring CS assertion, SCK synchronization, and optional HOLD suspension. Its internal architecture includes a 64-byte page latch, HV generator for EEPROM programming, and dual-level write protection: volatile WEL latch and nonvolatile BP0/BP1 bits controlling 0%, 25%, 50%, or 100% array lock.

It supports full 16-bit addressing (0000h–7FFFh) with automatic address roll-over during sequential reads, and enforces strict page-boundary alignment for multi-byte writes - crossing a 64-byte boundary wraps data to the start of the current page. The STATUS register is readable during writes, enabling real-time WIP bit polling without bus interruption.

Key Specifications

Pinout & Package

25LC256T-E/MF is packaged in an 8-lead DFN (Dual Flat No-lead) with wettable flank leads, measuring 2 mm × 3 mm × 0.55 mm (MSL3, RoHS-compliant). Pin 1 is marked by a dot; pin numbering follows standard DFN convention with CS on pin 1, SO on pin 2, WP on pin 3, VSS on pin 4, HOLD on pin 5, SCK on pin 6, SI on pin 7, and VCC on pin 8.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25DF256A-SSH-T and 25AA256-I/MF, the 25LC256T-E/MF delivers optimal balance of write speed (5 ms), voltage flexibility (2.5–5.5 V), and true byte-addressable EEPROM functionality - making it the preferred choice for mixed-signal microcontroller systems requiring reliable, low-overhead nonvolatile storage.

Availability

25LC256T-E/MF is available at Aetrix Electronics and suitable for automotive body controllers, industrial sensor nodes, medical infusion pumps, and smart energy meters requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for 25LC256T-E/MF 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 design and manufacturing operations.

The 25LC256T-E/MF belongs to Microchip's 25XX256 family of SPI EEPROMs, engineered for robust, low-power nonvolatile data storage in automotive, industrial, and medical systems where reliability and long-term data integrity are critical.

FAQ

What is the maximum clock frequency supported by the 25LC256T-E/MF?

The 25LC256T-E/MF supports up to 10 MHz clock frequency when VCC is between 4.5 V and 5.5 V. At 2.5–4.5 V, the maximum clock drops to 5 MHz, and at 1.8–2.5 V it is limited to 3 MHz. These values are specified in Table 1-2 of the DS20001822H datasheet and reflect guaranteed AC timing margins across temperature and voltage. The 25LC256T-E/MF does not support 10 MHz operation below 4.5 V.

Does the 25LC256T-E/MF support I²C or other interfaces besides SPI?

No, the 25LC256T-E/MF exclusively supports the SPI interface with dedicated SI, SO, SCK, and CS lines. It does not implement I²C, Microwire, UNI/O, or parallel interfaces. Its instruction set (READ, WRITE, WREN, RDSR, etc.) and timing diagrams are strictly SPI-compliant per Mode 0,0 and Mode 1,1 definitions. Any design requiring I²C must select a different part such as Microchip's 24AA256.

How does the HOLD pin function during an ongoing SPI transaction?

The HOLD pin suspends SPI communication mid-transaction when pulled low while SCK is low. During HOLD, SI, SCK, and SO enter high-impedance states and all inputs except CS are ignored. The 25LC256T-E/MF retains its internal state (address pointer, instruction phase), and resumes exactly where it left off when HOLD is returned high with SCK still low. This enables deterministic interrupt handling without reinitializing the command sequence.

What write protection mechanisms are implemented in the 25LC256T-E/MF?

The 25LC256T-E/MF implements three layered protections: (1) a volatile Write Enable Latch (WEL) reset on power-up and after each write, (2) nonvolatile Block Protection bits (BP0/BP1) enabling 0%/25%/50%/100% array lock, and (3) hardware WP pin control gated by the WPEN bit in the STATUS register. All three must be correctly configured to allow writes - no single mechanism alone permits unrestricted access.

Is the 25LC256T-E/MF pin-compatible with the 25AA256-I/MF?

Yes, the 25LC256T-E/MF and 25AA256-I/MF share identical 8-lead DFN (MF) packaging, pinout, instruction set, and AC/DC specifications - they are drop-in replacements in the same footprint. The key functional difference lies in supply voltage range (25LC256T-E/MF: 2.5–5.5 V; 25AA256-I/MF: 1.8–5.5 V) and corresponding max clock frequency scaling. Both operate identically within their overlapping 2.5–5.5 V range.