Microchip Technology 25LC256-E/SM

Overview

25LC256-E/SM from Microchip Technology is a 256 Kbit (32,768 × 8) SPI Serial EEPROM with 64-byte page write capability, 10 MHz max clock frequency at 4.5–5.5V, and industrial-grade operation from –40°C to +85°C. It features hardware write protection via WP pin and STATUS register, HOLD functionality for interrupt-safe bus suspension, and automotive AEC-Q100 qualification.

For engineers reviewing the 25LC256-E/SM datasheet, 25LC256-E/SM pinout, 25LC256-E/SM application, or 25LC256-E/SM equivalent, key selection criteria include VCC range (2.5–5.5V), endurance (1 million cycles), data retention (>200 years), and SOIC-8 (SM) package compatibility with legacy SPI-based microcontroller systems.

Technical Context

The 25LC256-E/SM implements a standard SPI Mode 0,0/Modes 0,0 and 1,1 interface with separate SI (input) and SO (output) lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS. Its internal architecture includes an 8-bit instruction register, page latches, HV generator for EEPROM programming, and a STATUS register with WIP, WEL, BP0/BP1, and WPEN bits.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate TWC (5 ms max internal write cycle); page writes are bounded to 64-byte aligned blocks and wrap on boundary violation. Standby current is 1 µA at 5.5V, supporting low-power embedded logging and configuration storage.

Key Specifications

Pinout & Package

25LC256-E/SM is housed in an 8-lead SOIC narrow-body package (JEDEC MS-012, Microchip designation SM), measuring 3.90 mm × 4.90 mm × 1.25 mm, with gull-wing leads and 1.27 mm pitch. Pin 1 is marked by a beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA256-I/SM, the 25LC256-E/SM offers guaranteed 2.5V operation and AEC-Q100 compliance at the cost of higher minimum supply voltage; versus AT25SF256A-SSHD-B, it provides simpler SPI integration and broader voltage tolerance but lacks hardware security extensions.

Availability

25LC256-E/SM is available at Aetrix Electronics and suitable for industrial PLC configuration storage, automotive body control modules, medical infusion pump calibration, and smart energy meter firmware patch storage requiring stable component supply and long-term obsolescence management.

Supply support for 25LC256-E/SM 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 devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LC256-E/SM belongs to Microchip's 25XX256 family of SPI Serial EEPROMs, designed specifically for reliable, low-pin-count nonvolatile storage in cost-sensitive, space-constrained embedded systems requiring robust data integrity and extended temperature operation.

FAQ

What is the maximum clock frequency supported by the 25LC256-E/SM?

The 25LC256-E/SM supports up to 10 MHz clock frequency when VCC is between 4.5V and 5.5V. At 2.5V ≤ VCC < 4.5V, the maximum clock drops to 5 MHz, and at 1.8V ≤ VCC < 2.5V, it is limited to 3 MHz. These limits ensure reliable setup/hold timing across voltage and temperature ranges, and are specified in Table 1-2 of the DS20001822H datasheet. The 25LC256-E/SM does not operate below 2.5V.

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

Yes, the 25LC256-E/SM supports page write operations with a fixed page size of 64 bytes. Up to 64 sequential bytes can be loaded into the page buffer before initiating the internal write cycle (TWC). Writing across a 64-byte boundary causes wraparound to the start of the same page - software must enforce address alignment. This behavior is documented in Section 2.3 and Figure 2-3 of the 25LC256-E/SM datasheet.

How does hardware write protection work on the 25LC256-E/SM?

Hardware write protection on the 25LC256-E/SM requires both the WP pin to be low and the WPEN bit (bit 7 of STATUS register) to be set high. When enabled, this combination disables writes to nonvolatile STATUS register bits (BP0, BP1, WPEN) but allows normal memory reads and writes. If WP is high or WPEN is low, hardware protection is inactive. This dual-control mechanism is defined in Table 2-1 and Section 2.6 of the DS20001822H datasheet.

Is the 25LC256-E/SM qualified for automotive applications?

Yes, the 25LC256-E/SM is AEC-Q100 qualified (Grade 2, –40°C to +105°C ambient), making it suitable for automotive body electronics, infotainment subsystems, and ADAS-related control modules. Its qualification covers stress tests including HTOL, TC, and ESD (>4 kV HBM), and it is rated for industrial temperature range (–40°C to +85°C) in standard operation. Full qualification details are in the device selection table on page 1 of DS20001822H.

What is the endurance and data retention specification for the 25LC256-E/SM?

The 25LC256-E/SM guarantees 1,000,000 erase/write cycles and greater than 200 years of data retention at 25°C, per characterization data in Table 1-3 of DS20001822H. Endurance is tested at 25°C and VCC = 5.5V; retention is extrapolated using Arrhenius modeling. Real-world retention decreases with elevated temperature - at 85°C, retention exceeds 40 years. These figures apply to the 25LC256-E/SM under specified operating conditions.