Microchip Technology AT25040B-MAHL-E

Overview

AT25040B-MAHL-E from Microchip Technology is a 4-Kbit SPI Serial EEPROM (512 × 8) with industrial-grade operation (−40°C to +85°C), 1.8V–5.5V supply range, and 20 MHz max clock rate at 5V. It features hardware/software write protection, 8-byte page write mode, and self-timed write cycles ≤5 ms - deployed in embedded control systems for firmware parameter storage and calibration data retention.

For engineers reviewing the AT25040B-MAHL-E datasheet, AT25040B-MAHL-E pinout, AT25040B-MAHL-E application, or AT25040B-MAHL-E equivalent, key selection criteria include SPI Mode 0/3 compatibility, VCC voltage scalability across 1.8–5.5V, block-level write protection granularity (1/4, 1/2, or full array), HOLD/CS-controlled suspend capability, and guaranteed 1M write cycles with 100-year data retention.

Technical Context

The AT25040B-MAHL-E implements a synchronous SPI slave interface with fixed MSB-first serial framing, rising-edge input sampling (SI), and falling-edge output latching (SO). Its internal architecture includes a nonvolatile STATUS register controlling BP1/BP0 block protection bits, WEL latch, and RDY/BSY flag - all accessible via dedicated opcodes (RDSR, WRSR, WREN).

It supports dual-voltage timing: AC characteristics scale with VCC (e.g., tWH = 20 ns @ 5V, 80 ns @ 1.8V), and power-up requires ≥100 µs stabilization post-VCC threshold (VPOR ≤1.5 V) before instruction acceptance. The HOLD pin suspends serial communication without resetting state, while WP pin disables writes independently of software enable status.

Key Specifications

Pinout & Package

AT25040B-MAHL-E is packaged in an 8-lead SOIC (Small Outline Integrated Circuit) with standard JEDEC MS-012AC footprint (5.3 mm × 4.4 mm, 1.27 mm pitch). This package supports reflow soldering per J-STD-020 and is RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95040-DRMN6TP/K and 25AA040AT-I/OT, the AT25040B-MAHL-E uniquely combines HOLD functionality, 20 MHz speed at 5V, and consistent BP bit implementation across Microchip's AT25xxx-B family - simplifying firmware reuse and enabling deterministic interrupt handling in time-critical applications.

Availability

AT25040B-MAHL-E is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, and automotive body control modules requiring stable component supply across extended temperature and voltage ranges.

Supply support for AT25040B-MAHL-E 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 AT25xxx-B family was designed specifically for reliable, low-power nonvolatile storage in resource-constrained embedded systems - emphasizing SPI interoperability, industrial temperature resilience, and long-term data integrity.

FAQ

What is the maximum SPI clock frequency supported by AT25040B-MAHL-E?

The AT25040B-MAHL-E supports up to 20 MHz SCK frequency when VCC is 4.5V–5.5V, 10 MHz at 2.5V–5.5V, and 5 MHz at 1.8V–5.5V. These graded timing specifications ensure robust signal integrity across its full 1.8V–5.5V operating range. All timing parameters - including tWH, tWL, and tSU - scale accordingly, as defined in Table 4-3 of the DS20006251A datasheet. The AT25040B-MAHL-E maintains full functionality across this range without configuration changes.

Does AT25040B-MAHL-E support both SPI Mode 0 and Mode 3?

Yes, AT25040B-MAHL-E explicitly supports SPI Modes 0 (CPOL=0, CPHA=0) and 3 (CPOL=1, CPHA=1). In both modes, data is latched on the rising edge of SCK and output on the falling edge. The only difference is SCK idle polarity: low in Mode 0, high in Mode 3. The AT25040B-MAHL-E requires matching SCK idle state before and after CS assertion. Mode 0 is used in all timing diagrams and recommended for new designs unless legacy compatibility dictates Mode 3.

How does the HOLD pin function during an active write cycle in AT25040B-MAHL-E?

The HOLD pin in AT25040B-MAHL-E has no effect on an ongoing internal write cycle - it only suspends serial communication (SI/SO/SCK interaction) while CS remains asserted. If a WRITE command has already triggered the self-timed 5 ms erase-program sequence, asserting HOLD will pause further instruction input but will not interrupt the write. The AT25040B-MAHL-E continues programming and sets RDY/BSY=0 upon completion. HOLD is therefore safe to use during background writes without data corruption risk.

What write protection mechanisms are implemented in AT25040B-MAHL-E?

AT25040B-MAHL-E provides dual-layer write protection: hardware-based via the WP pin (low = all writes disabled), and software-configurable via BP1/BP0 bits in the STATUS register (enabling 1/4, 1/2, or full array lock). WP overrides software settings - if WP is low, no write commands execute regardless of BP or WEL state. The AT25040B-MAHL-E also requires WREN instruction and WEL=1 for any write, adding a third logical gate. This three-tier scheme ensures robust defense against accidental or malicious overwrites.

Is AT25040B-MAHL-E pin-compatible with other members of the AT25xxx-B family?

Yes, AT25040B-MAHL-E shares identical pinout, package dimensions, and electrical interface with AT25010B and AT25020B in the same SOIC-8 package (MAHL-E). All three use the same CS/SO/WP/GND/SI/SCK/HOLD/VCC arrangement and command set. The only functional difference is memory size (1K/2K/4K), reflected in address bit usage (A8 is significant only in AT25040B). Firmware written for one can run on another with minor address-range adjustments - making AT25040B-MAHL-E a drop-in upgrade path.