Microchip Technology 25LC256-H/SN

Overview

25LC256-H/SN from Microchip Technology is a 256-Kbit serial EEPROM organized as 32,768 × 8-bit memory, supporting SPI interface with 5 MHz max clock, 64-byte page write, and extended temperature operation from –40°C to +150°C. It features hardware write protection via WP pin, HOLD suspend functionality, and AEC-Q100 qualification for automotive engine control modules.

For engineers reviewing the 25LC256-H/SN datasheet, 25LC256-H/SN pinout, 25LC256-H/SN application, or 25LC256-H/SN equivalent, key selection criteria include high-temp endurance (>1M cycles), block-level write protection (0/¼/½/all array), self-timed 6 ms write cycle, and SOIC-8 packaging compatible with industrial sensor nodes and automotive powertrain ECUs.

Technical Context

The 25LC256-H/SN implements a standard SPI Mode 0,0 (CPOL=0, CPHA=0) interface with separate SI and SO lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS. Its internal architecture includes an 8-bit instruction register, page latches, and HV generator for EEPROM programming.

It supports byte and page write operations with automatic address increment during sequential read, and uses a write enable latch (WEL) that must be set via WREN before any write - reset on power-up, WRDI, WRITE, or WRSR completion. The STATUS register provides real-time WIP flag and BP0/BP1 block protection configuration.

Key Specifications

Pinout & Package

8-Lead SOIC (SN) package, 3.90 mm body width, JEDEC MS-012AC compliant, RoHS-compliant matte tin lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25DF256A-SSH-T and BR25H256FJ-WE2, the 25LC256-H/SN uniquely combines AEC-Q100 Grade 0 qualification, HOLD pin for deterministic interrupt handling, and WPEN-controlled hardware write protection - making it the only option qualified for under-hood automotive control modules requiring both reliability and real-time responsiveness.

Availability

25LC256-H/SN is available at Aetrix Electronics and suitable for automotive powertrain systems, industrial sensor nodes, and medical infusion pumps requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 25LC256-H/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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LCxxx family was designed specifically for robust, high-reliability serial EEPROM applications in automotive, industrial, and medical systems where extended temperature operation and AEC-Q100 compliance are mandatory.

FAQ

What is the maximum clock frequency supported by the 25LC256-H/SN?

The 25LC256-H/SN supports up to 5 MHz at VCC = 4.5–5.5V and 3 MHz at VCC = 2.5–4.5V. These limits are defined by AC timing parameters including Tsu (data setup time) and THD (data hold time), which tighten at lower supply voltages. Exceeding these frequencies risks read/write corruption due to violated setup/hold margins, especially at temperature extremes.

Does the 25LC256-H/SN require external pull-up resistors on its SPI lines?

The 25LC256-H/SN does not require external pull-ups on SI, SCK, or CS - these inputs have CMOS-compatible thresholds and function correctly with standard microcontroller GPIO outputs. However, SO should be pulled up (typically 4.7 kΩ to VCC) when shared with other devices to ensure clean high-Z release and prevent bus contention during deselection.

How does the HOLD pin function during an active write cycle in the 25LC256-H/SN?

The HOLD pin has no effect once an internal write cycle (TWC) has started - it cannot pause or abort an ongoing 6 ms erase-and-write operation. HOLD only suspends serial communication (instruction/address/data transfer) before the CS-rising-edge trigger that initiates TWC. During TWC, the STATUS register WIP bit remains '1', and SO stays high-Z regardless of HOLD state.

What happens if a page write crosses a 64-byte boundary in the 25LC256-H/SN?

If a page write command attempts to cross a 64-byte physical boundary (e.g., writing bytes 60–67 starting at address 0x003C), data wraps around to the start of the same page (address 0x0000 in this example), overwriting prior content. The device does not auto-advance to the next page. Application firmware must enforce page alignment or split writes at boundaries to prevent unintended data loss.

Is the 25LC256-H/SN pin-compatible with earlier 25LC256 variants like 25LC256-I/SN?

Yes, the 25LC256-H/SN shares identical SOIC-8 (SN) package dimensions, pinout, and electrical interface with all 25LC256 variants including 25LC256-I/SN and 25LC256-E/SN. The 'H' suffix denotes the extended –40°C to +150°C temperature grade, but mechanical and functional compatibility is maintained across grades for drop-in replacement in existing layouts.