Microchip Technology 25LC040AT-I/MNY

Overview

25LC040AT-I/MNY from Microchip Technology Inc. is a 4 Kbit (512 × 8) SPI Serial EEPROM with 16-byte page write capability, 10 MHz max clock frequency at 4.5–5.5 V, and industrial temperature range (−40°C to +85°C). It features hardware write protection (WP pin), HOLD function for interrupt-safe serial pauses, and block-level array protection (none/¼/½/all). Used in embedded systems for storing calibration data, configuration settings, and firmware parameters.

For engineers reviewing the 25LC040AT-I/MNY datasheet, 25LC040AT-I/MNY pinout, 25LC040AT-I/MNY application, or 25LC040AT-I/MNY equivalent, key selection criteria include VCC operating range (2.5–5.5 V), page write timing (≤5 ms), endurance (1 million cycles), data retention (>200 years), and compatibility with standard SPI Mode 0,0 and Mode 1,1 interfaces.

Technical Context

The 25LC040AT-I/MNY implements a true SPI-compatible serial interface with separate SI (MOSI) and SO (MISO) lines, CS-controlled selection, and SCK-synchronized transfers. Its internal architecture includes a 512-byte EEPROM array, page latches, status register (WIP/WEL/BP0/BP1), and HV generator for write/erase operations.

It supports byte and page write modes, sequential read with automatic address increment, and HOLD functionality that tri-states SO while preserving internal state. Write enable latch (WEL) must be set via WREN instruction before any nonvolatile write, and is automatically reset after successful write or power-up.

Key Specifications

Pinout & Package

25LC040AT-I/MNY is packaged in an 8-lead DFN (2 mm × 3 mm, 0.5 mm pitch) with exposed pad. Pin 1 is marked by laser dot; exposed pad may be connected to VSS or left floating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA040AT-I/MNY and AT25040B-MAHL-T, the 25LC040AT-I/MNY offers optimal balance of 3.3/5 V compatibility, low standby current, and DFN footprint - making it preferred for space-constrained industrial controllers where 1.8 V operation is unnecessary.

Availability

25LC040AT-I/MNY is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive body electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for 25LC040AT-I/MNY 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 family was designed for reliable, low-pin-count nonvolatile storage in resource-constrained embedded systems - emphasizing SPI simplicity, hardware write safety, and extended temperature resilience.

FAQ

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

The 25LC040AT-I/MNY supports up to 10 MHz clock frequency when VCC is between 4.5 V and 5.5 V. At 2.5–4.5 V, the maximum clock drops to 5 MHz, and it is not rated for operation below 2.5 V. This graded timing ensures robust signal integrity across its specified supply range, and all AC parameters in the DS21827H datasheet are validated per voltage bin.

Does the 25LC040AT-I/MNY require external pull-up resistors on its SPI lines?

No, the 25LC040AT-I/MNY does not require external pull-ups on SI, SO, or SCK - these pins are actively driven. However, CS and WP are active-low inputs with internal weak pull-ups disabled by default; external pull-ups (e.g., 10 kΩ to VCC) are recommended for noise immunity in noisy industrial environments. HOLD also benefits from a pull-up if not actively controlled.

How does the page write boundary work in the 25LC040AT-I/MNY?

The 25LC040AT-I/MNY has a fixed 16-byte page size, where each page starts at addresses ending in 00h (e.g., 000h, 010h, ..., 1F0h). If a page write crosses a boundary - for example, starting at 00Fh and writing 16 bytes - the 17th byte wraps to 000h and overwrites prior data. Software must validate address alignment and limit writes to ≤16 bytes within one page to prevent corruption.

Can the 25LC040AT-I/MNY be used in automotive applications?

The 25LC040AT-I/MNY is rated for Industrial temperature range (−40°C to +85°C), not Automotive (−40°C to +125°C). For automotive use, Microchip specifies the 25LC040AE variant (suffix 'E'). Using the 25LC040AT-I/MNY in under-hood or other high-temp automotive zones risks parametric drift and reduced endurance; always select the 'E' grade for AEC-Q100-relevant deployments.

What happens to the write enable latch after a successful write operation on the 25LC040AT-I/MNY?

After a successful byte, page, or STATUS register write, the write enable latch (WEL bit) in the 25LC040AT-I/MNY is automatically reset to '0'. This means the next write attempt will fail unless WREN is reissued. The latch is also reset on power-up, WRDI execution, WRSR execution, or when the WP pin is pulled low - ensuring failsafe write protection by default.