Microchip Technology 25LC040AT-I/SN

Overview

25LC040AT-I/SN from Microchip Technology Inc. is a 4 Kbit Serial SPI 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 serial communication - used in embedded system configuration storage, sensor calibration data retention, and firmware parameter backup.

For engineers reviewing the 25LC040AT-I/SN datasheet, 25LC040AT-I/SN pinout, 25LC040AT-I/SN application, or 25LC040AT-I/SN equivalent, key selection criteria include VCC range compatibility (2.5–5.5V), SPI Mode 0/1 support, page write boundary handling, WP/HOLD pin behavior under interrupt conditions, and endurance requirements (>1M cycles) for field-updatable systems.

Technical Context

The 25LC040AT-I/SN implements a standard SPI interface with separate SI (data in), SO (data out), SCK (clock), CS (chip select), WP (write-protect), and HOLD (serial pause) signals. Its internal architecture includes a nonvolatile EEPROM array, page latches, status register (WIP/WEL/BP0/BP1), and HV generator for write/erase operations.

It supports byte and page write modes with self-timed internal write cycles (≤5 ms), automatic address roll-over during sequential read, and configurable block protection (none/1/4/1/2/all array). The device resets its write enable latch on power-up, WRDI, WRSR, WRITE completion, or WP low assertion - enforcing strict write gating.

Key Specifications

Pinout & Package

25LC040AT-I/SN uses an 8-lead SOIC package (SN suffix), measuring 3.9 mm × 4.9 mm × 1.75 mm, with gull-wing leads and Pb-free RoHS-compliant finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC040AT-I/SN, the 25AA040AT-I/SN enables lower-voltage systems but lacks guaranteed 2.5V operation margin, while the AT25040B-MAU-T adds automotive qualification and compact packaging at the cost of HOLD support and SOIC compatibility.

Availability

25LC040AT-I/SN is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, automotive body electronics, and smart metering applications requiring stable component supply, long-term data integrity, and SPI-based nonvolatile storage.

Supply support for 25LC040AT-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, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LC040A family is designed for embedded systems requiring reliable, low-power, SPI-compatible nonvolatile memory - optimized for configuration storage, calibration data, and firmware metadata in industrial, medical, and automotive applications.

FAQ

What is the maximum clock frequency supported by the 25LC040AT-I/SN?

The 25LC040AT-I/SN supports up to 10 MHz clock frequency when VCC is 4.5V to 5.5V. At 2.5V ≤ VCC < 4.5V, the maximum clock is 5 MHz, and at 1.8V ≤ VCC < 2.5V, it drops to 3 MHz. These limits are defined in Table 1-2 AC Characteristics and ensure reliable setup/hold timing across voltage and temperature ranges. The 25LC040AT-I/SN must operate within these bounds to guarantee correct SPI communication and data integrity.

Does the 25LC040AT-I/SN support page write operations, and what is the page size?

Yes, the 25LC040AT-I/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 triggering an internal write cycle. Page boundaries align to addresses ending in 0x0F (e.g., 0x00–0x0F, 0x10–0x1F). Writing across a boundary wraps data to the start of the same page - a behavior the host firmware must manage. The 25LC040AT-I/SN's page write capability significantly reduces SPI transaction overhead compared to byte writes.

How does the HOLD pin function on the 25LC040AT-I/SN, and what are its timing requirements?

The HOLD pin on the 25LC040AT-I/SN suspends ongoing SPI communication without resetting the internal state. To activate HOLD, the pin must be pulled low while SCK is low; deactivation requires bringing HOLD high while SCK remains low. During HOLD, SI, SO, and SCK are tri-stated, and inputs are ignored except CS. Minimum HOLD setup/hold times are 20–80 ns depending on VCC. This feature allows the host MCU to service urgent interrupts and resume exactly where the 25LC040AT-I/SN left off - critical for deterministic real-time systems.

What write protection mechanisms does the 25LC040AT-I/SN provide?

The 25LC040AT-I/SN implements three layered write protections: (1) hardware WP pin - disables all writes when low; (2) software-controlled Block Protection bits (BP0/BP1) - configure protection of none/1/4/1/2/all memory segments; and (3) Write Enable Latch (WEL) - must be set via WREN instruction before any write. All three must permit writing simultaneously. The 25LC040AT-I/SN resets WEL on power-up, WRDI, WRSR, WRITE completion, or WP low - ensuring failsafe default protection.

Is the 25LC040AT-I/SN RoHS compliant and lead-free?

Yes, the 25LC040AT-I/SN is Pb-free and RoHS compliant, as confirmed in the device selection table and packaging section of DS21827H. The "T" in the part number denotes tape-and-reel packaging, and the "SN" suffix specifies the 8-lead SOIC package with matte tin (Sn) lead finish. Microchip's Pb-free JEDEC designator (3e) appears on outer packaging. This compliance meets EU Directive 2011/65/EU and supports environmentally responsible manufacturing for the 25LC040AT-I/SN.