Microchip Technology 25LC040A-H/SN

Overview

25LC040A-H/SN from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI serial EEPROM with extended temperature operation (−40°C to +150°C), 5 MHz max clock, 16-byte page write capability, and hardware write protection via WP pin. It operates from 2.5V–5.5V and supports byte/page writes, sequential read, and block-level write protection for automotive engine control units.

For engineers reviewing the 25LC040A-H/SN datasheet, 25LC040A-H/SN pinout, 25LC040A-H/SN application, or 25LC040A-H/SN equivalent, this device is selected for high-temp embedded systems requiring nonvolatile data storage with SPI interface compatibility, deterministic 6 ms max write cycle time, and AEC-Q100-aligned reliability at 150°C ambient.

Technical Context

The 25LC040A-H/SN implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data in) and SO (data out) lines, CS-controlled selection, and HOLD pin for transaction suspension without reset. Its internal architecture includes an 8-bit instruction register, status register with WIP/WEL/BP bits, and EEPROM array partitioned into four addressable blocks for configurable protection.

Write operations require explicit WREN instruction before WRITE or WRSR commands; the write enable latch resets automatically after each successful write or on WP low assertion. All timing parameters-including TCSS (100 ns min CS setup), TV (100 ns max output valid), and TWC (6 ms max internal write)-are guaranteed across −40°C to +150°C at VCC = 2.5V–5.5V.

Key Specifications

Pinout & Package

25LC040A-H/SN is housed in an 8-lead SOIC (SN) package, Pb-free and RoHS compliant, with 3.90 mm body width and standard JEDEC MS-012AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25040B-MAHL-T and M95040-DRMN3TP/K, the 25LC040A-H/SN uniquely delivers guaranteed 150°C operation with proven AEC-Q100 alignment, making it the only option qualified for direct mounting in high-heat zones without derating or thermal shielding.

Availability

25LC040A-H/SN is available at Aetrix Electronics and suitable for automotive engine management, industrial motor drives, medical infusion pumps, and avionics sensor modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 25LC040A-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 U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and memory products, with global design centers and ISO/TS 16949-certified manufacturing.

The 25LCXXXA family was designed specifically for high-reliability embedded systems needing SPI-compatible nonvolatile storage in harsh thermal environments - targeting automotive, industrial, and aerospace applications where data integrity at temperature extremes is non-negotiable.

FAQ

What is the maximum clock frequency supported by the 25LC040A-H/SN?

The 25LC040A-H/SN supports a maximum clock frequency of 5 MHz when VCC is between 4.5V and 5.5V. At lower supply voltages (2.5V ≤ VCC < 4.5V), the maximum clock speed is reduced to 3 MHz. These limits are guaranteed across the full −40°C to +150°C operating range and are defined in Table 1-2 of the DS22136B datasheet.

Does the 25LC040A-H/SN support page write operations, and what is the page size?

Yes, the 25LC040A-H/SN supports page write operations with a fixed page size of 16 bytes. This allows up to 16 consecutive bytes to be loaded into the internal page buffer and written in a single internal cycle. Page boundaries align to addresses ending in 0x00–0x0F, and crossing a boundary causes wraparound within the same page - a behavior documented in Figure 3-3 and Section 3.3 of DS22136B.

How does the Write-Protect (WP) pin function on the 25LC040A-H/SN?

The WP pin on the 25LC040A-H/SN is a hardware-level write inhibit signal. When pulled low, it disables all writes to both the memory array and STATUS register - regardless of WREN state or BP bit settings. However, it does not abort an already-initiated write cycle. The WP pin's behavior is fully defined in Table 5-1 and Section 2.3 of the DS22136B datasheet.

What is the internal write cycle time for the 25LC040A-H/SN, and is polling required?

The 25LC040A-H/SN has a maximum internal write cycle time (TWC) of 6 ms, beginning on the rising edge of CS after a valid write command sequence. While polling the WIP bit in the STATUS register is optional, it provides precise completion detection. The RDSR instruction (0x05) reads the STATUS register at any time - even during write - and returns WIP=0 when complete.

Is the 25LC040A-H/SN compatible with standard SPI Mode 0,0, and how is data transferred?

Yes, the 25LC040A-H/SN is fully compatible with SPI Mode 0,0 (CPOL = 0, CPHA = 0). Data is sampled on the rising edge of SCK (SI input) and updated on the falling edge (SO output). Instructions, addresses, and data are transmitted MSB-first. This timing is confirmed in Section 2.5 and Figure 1-2 of DS22136B, and matches standard PIC® MCU SPI peripheral configurations.