Microchip Technology 25LC040A-M/SN

Overview

25LC040A-M/SN from Microchip Technology Inc. is a 4 Kbit SPI Serial EEPROM with 512 × 8-bit organization, 16-byte page write capability, and industrial temperature range (–40°C to +85°C). It operates from 2.5V to 5.5V, supports up to 10 MHz clock frequency, and features hardware write protection via WP pin and HOLD functionality for interrupt-safe bus suspension. It is widely used in microcontroller-based systems for parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 25LC040A-M/SN datasheet, 25LC040A-M/SN pinout, 25LC040A-M/SN application, or 25LC040A-M/SN equivalent, key selection criteria include VCC range compatibility (2.5–5.5V), SPI timing compliance at target clock speed, page boundary handling in firmware, WP/HOLD signal routing, and package footprint (8-lead SOIC).

Technical Context

The 25LC040A-M/SN implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, and optional HOLD/WP control. Its internal architecture includes a 512-byte EEPROM array, page latches, status register (WIP, WEL, BP0/BP1), and high-voltage generator for write/erase operations.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms); read operations support sequential addressing with automatic address roll-over at 0x1FF. Block protection is configurable via STATUS register to lock 0%, 25%, 50%, or 100% of memory.

Key Specifications

Pinout & Package

25LC040A-M/SN is packaged in an 8-lead SOIC (Small Outline Integrated Circuit) with standard 150-mil body width and 1.27 mm pitch. Pin 1 is marked by laser dot or notch; package is Pb-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA040A-I/SN, the 25LC040A-M/SN offers tighter VCC min (2.5V vs. 1.8V) but identical industrial temp rating and page write behavior; versus AT25040B-MAU-10, it uses Microchip's native instruction set and protection matrix, reducing integration risk in existing PIC® or SAM-based platforms.

Availability

25LC040A-M/SN is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, and automotive body control modules requiring stable component supply, long-term obsolescence management, and RoHS-compliant packaging.

Supply support for 25LC040A-M/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 devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LC040A belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile storage in cost-sensitive embedded systems across industrial, medical, and automotive markets.

FAQ

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

The 25LC040A-M/SN 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 (not applicable to 25LC040A-M/SN due to its 2.5V minimum), it would be 3 MHz. These limits ensure reliable setup/hold timing and noise margin across voltage grades. The 25LC040A-M/SN datasheet specifies these values in Table 1-2 (AC Characteristics).

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

Yes, the 25LC040A-M/SN supports page write mode with a fixed page size of 16 bytes. This allows up to 16 consecutive bytes to be loaded into the page buffer before initiating the internal write cycle. Firmware must ensure all addresses in a single page write fall within the same 16-byte boundary (e.g., 0x00–0x0F, 0x10–0x1F); crossing boundaries causes wrap-around overwrite. The 25LC040A-M/SN's page write capability improves write efficiency compared to byte-by-byte programming.

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

The WP pin on the 25LC040A-M/SN is a hardware-level write inhibitor: when pulled low, it disables all write operations to both the memory array and STATUS register, regardless of WREN status or BP bit settings. It does not affect read operations or command execution (e.g., RDSR still works). The 25LC040A-M/SN's WP pin provides fail-safe protection against accidental writes during power transitions or software faults, complementing the software-configurable block protection bits.

What is the operating temperature range for the 25LC040A-M/SN?

The 25LC040A-M/SN is rated for the Industrial temperature range of –40°C to +85°C. This is explicitly stated in the Device Selection Table and confirmed in Section 1.0 (Electrical Characteristics) of the DS21827H datasheet. It is not qualified for the Automotive (–40°C to +125°C) grade - that applies only to the 25LC040A-E variant. The "M" in 25LC040A-M/SN denotes Industrial temperature grade, and "SN" indicates SOIC packaging.

Can the 25LC040A-M/SN be used with 3.3V microcontrollers without level shifting?

Yes, the 25LC040A-M/SN is fully compatible with 3.3V microcontrollers. Its VCC range is 2.5V to 5.5V, and its input thresholds (VIH1 = 0.7×VCC, VIL1 = 0.3×VCC) ensure reliable recognition of 3.3V logic levels. Output drive strength (VOL ≤ 0.4V at 2.1 mA) meets standard CMOS fan-out requirements. No level-shifting circuitry is needed when interfacing with 3.3V SPI masters - a key advantage of the 25LC040A-M/SN in mixed-voltage embedded designs.