Microchip Technology 25LC040-I/SN

Overview

25LC040-I/SN from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI-compatible serial EEPROM with 2.5–5.5 V supply range, 2 MHz max clock frequency, and industrial temperature support (−40°C to +85°C). It features 16-byte page write capability, hardware write protection via WP pin, and HOLD functionality for interrupt-safe bus suspension - deployed in embedded control systems for parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 25LC040-I/SN datasheet, 25LC040-I/SN pinout, 25LC040-I/SN application, or 25LC040-I/SN equivalent, this page delivers verified electrical specs, validated SOIC-8 pin mapping, real-world use cases in industrial controllers and sensor nodes, and two confirmed alternative parts with documented functional and parametric differences.

Technical Context

The 25LC040-I/SN implements a standard SPI Mode 0,0 interface (CPOL=0, CPHA=0) 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, auto-incrementing address pointer for sequential reads, and a nonvolatile STATUS register controlling block write protection (BP0/BP1) and monitoring WIP/WEL status.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms), while read operations support continuous byte streaming with automatic address rollover at 01FFh. Hardware protections include power-on reset of write enable latch, WP-pin override, and built-in ESD tolerance (>4 kV).

Key Specifications

Pinout & Package

25LC040-I/SN is packaged in 8-pin SOIC (SN), 150-mil body width, JEDEC MS-012 compliant. Pin 1 is marked with dot or bevel; pin numbering follows standard SOIC convention (counterclockwise from top-left corner).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA040-I/SN, the 25LC040-I/SN provides 2× faster SPI clock support (2 MHz vs. 1 MHz) at the cost of minimum supply voltage (2.5 V vs. 1.8 V); versus AT25040B-MAU-10, it trades raw speed for broader compatibility with legacy 2 MHz SPI peripherals and simpler timing closure.

Availability

25LC040-I/SN is available at Aetrix Electronics and suitable for industrial control systems, sensor calibration modules, and medical device configuration storage requiring stable component supply and long-term lifecycle support.

Supply support for 25LC040-I/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, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LC040 belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for reliable, low-power, pin-efficient nonvolatile storage in cost-sensitive embedded systems with constrained PCB area.

FAQ

What is the maximum clock frequency supported by the 25LC040-I/SN?

The 25LC040-I/SN supports a maximum SPI clock frequency of 2 MHz when VCC is 2.5 V or higher. At lower supply voltages, the maximum clock rate decreases per datasheet Table 1-2 - for example, 1 MHz at VCC = 1.8–2.5 V. This specification ensures reliable setup/hold timing margins across industrial temperature and voltage ranges.

Does the 25LC040-I/SN support page write operations?

Yes, the 25LC040-I/SN supports 16-byte page write operations. The device organizes its 512-byte memory into 32 pages of 16 bytes each. Page writes improve programming efficiency over byte writes, but crossing page boundaries during a single write sequence causes wraparound and unintended overwrites - firmware must enforce page alignment.

How does the HOLD pin function on the 25LC040-I/SN?

The HOLD pin on the 25LC040-I/SN suspends ongoing SPI communication without resetting the internal address counter. When asserted low during an active CS cycle, it tri-states SO, SI, and SCK, allowing the host MCU to service interrupts. Communication resumes from the exact bit position when HOLD is released while SCK is low - preserving transaction integrity.

What write protection mechanisms does the 25LC040-I/SN provide?

The 25LC040-I/SN provides dual-layer write protection: hardware via the WP pin (disables all writes when low), and software-configurable block protection via BP0/BP1 bits in the STATUS register. These bits allow locking 0%, 25%, 50%, or 100% of the memory array - protecting critical calibration or boot code from accidental overwrite.

Is the 25LC040-I/SN pin-compatible with other members of the 25XX040 family?

Yes, the 25LC040-I/SN is pin-compatible with 25AA040-I/SN and 25C040-I/SN in SOIC-8 (SN) packaging. All share identical pinout, SPI command set, and memory organization. Differences lie in VCC range (2.5–5.5 V), max clock (2 MHz), and temperature grading - making them direct drop-in replacements where voltage and speed requirements align.