Microchip Technology 25AA040AT-I/MNY

Overview

25AA040AT-I/MNY from Microchip Technology is a 4 Kbit SPI Serial EEPROM with 512 × 8-bit organization, 1.8–5.5 V supply range, and industrial temperature rating (−40°C to +85°C). It supports up to 10 MHz clock frequency, 16-byte page write, and hardware write protection via WP pin - used for firmware storage, calibration data retention, and configuration memory in embedded controllers.

For engineers reviewing the 25AA040AT-I/MNY datasheet, 25AA040AT-I/MNY pinout, 25AA040AT-I/MNY application, or 25AA040AT-I/MNY equivalent, key selection criteria include SPI timing compliance at 1.8 V, block write-protection granularity (none/¼/½/all), HOLD pin support for interrupt-safe bus arbitration, and 1,000,000 write-cycle endurance.

Technical Context

The 25AA040AT-I/MNY implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (input) and SO (output) lines, CS-controlled selection, and SCK-synchronized data transfer. Its internal architecture includes an 8-bit instruction register, page latches, and high-voltage generation circuitry for EEPROM programming.

It features dual write-protection mechanisms: nonvolatile BP0/BP1 bits in the STATUS register (configurable via WRSR) and hardware WP pin assertion. The HOLD pin enables mid-transaction suspension without sequence restart, and the WIP bit allows polling-based write completion detection.

Key Specifications

Pinout & Package

25AA040AT-I/MNY is packaged in an 8-lead 2×3 mm DFN (MNY) with exposed pad, RoHS-compliant and Pb-free. Pin 1 is laser-marked; 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 SPI EEPROM applications.

Compared with 25AA040AT-I/MNY, the SOIC-packaged 25AA040A-I/SN offers identical electrical behavior but larger footprint and lower thermal performance, while AT25040B-MAHL-T provides higher clock tolerance at the cost of non-drop-in STATUS register compatibility.

Availability

25AA040AT-I/MNY is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, and automotive body control modules requiring stable component supply across extended product lifecycles.

Supply support for 25AA040AT-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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25AA040A family was designed specifically for reliable, low-power, SPI-based nonvolatile data storage in cost-sensitive embedded systems - emphasizing write-protection integrity, wide voltage operation, and industrial-grade reliability.

FAQ

What is the maximum SPI clock frequency supported by the 25AA040AT-I/MNY?

The 25AA040AT-I/MNY supports up to 10 MHz clock frequency when VCC is 4.5 V to 5.5 V, 5 MHz at 2.5 V to 4.5 V, and 3 MHz at 1.8 V to 2.5 V. These limits ensure setup/hold timing margins are met across voltage and temperature ranges - verified per DS21827H AC Characteristics Table 1-2.

Does the 25AA040AT-I/MNY require an external pull-up resistor on the SO pin?

No, the 25AA040AT-I/MNY SO pin is internally driven and does not require an external pull-up. It operates as a tri-state CMOS output: actively driven high/low during read cycles and placed in high-impedance state when CS is high or HOLD is asserted - confirmed in Pin Descriptions section 3.2 of DS21827H.

How does the WP pin interact with the write-enable latch in the 25AA040AT-I/MNY?

In the 25AA040AT-I/MNY, asserting WP low resets the write-enable latch (WEL) and blocks all writes regardless of WEL state - even if WREN was previously issued. This hardware lock takes precedence over software-controlled protection and remains active until WP returns high, as defined in Table 2-4 and section 3.3 of DS21827H.

Can the 25AA040AT-I/MNY be used with a 1.8 V microcontroller without level shifting?

Yes, the 25AA040AT-I/MNY is fully specified down to 1.8 V VCC and supports 1.8 V logic levels: VIH1 = 0.7×VCC (min 1.26 V) and VIL2 = 0.2×VCC (max 0.36 V) - enabling direct connection to 1.8 V GPIOs without translators, per DC Characteristics Table 1-1 in DS21827H.

What happens if a page write crosses a 16-byte boundary in the 25AA040AT-I/MNY?

If a page write command attempts to cross a 16-byte boundary (e.g., writing 16 bytes starting at address 0x0F), the 25AA040AT-I/MNY wraps the excess bytes to the start of the same page (0x00), overwriting prior data - not advancing to the next page. This behavior is explicitly documented in section 2.3 and Note under Figure 2-3 of DS21827H.