Microchip Technology AT25040-10PI-2.7

Overview

AT25040-10PI-2.7 from Atmel (now Microchip) is a 4-kbit SPI serial EEPROM organized as 512 × 8-bit memory, operating from 2.7V to 5.5V, supporting 3.0 MHz clock rate at 5V, featuring 8-byte page write and hardware/software write protection via WP pin and status register. It is used in industrial control systems for parameter storage and calibration data retention.

For engineers reviewing the AT25040-10PI-2.7 datasheet, AT25040-10PI-2.7 pinout, AT25040-10PI-2.7 application, or AT25040-10PI-2.7 equivalent, key selection considerations include VCC range compatibility (2.7–5.5V), SPI Mode 0/3 support, block write protection granularity (1/4, 1/2, full array), and PDIP-8 packaging for through-hole prototyping and legacy board replacement.

Technical Context

The AT25040-10PI-2.7 implements a synchronous SPI slave interface with separate SI/SO pins, MSB-first data transfer, and CS-driven command framing. Its internal architecture includes an 8-bit instruction register handling WREN, WRITE, READ, RDSR, WRSR, and WRDI op-codes.

It features a nonvolatile status register with BP1/BP0 bits controlling block write protection across four address segments, and RDY/WEN flags indicating write cycle completion and write enable state. The HOLD pin enables communication suspension without sequence reset, while WP provides hardware-level write inhibition independent of software commands.

Key Specifications

Pinout & Package

AT25040-10PI-2.7 uses an 8-lead PDIP (0.300" wide, JEDEC MS-001 BA variant) package with through-hole mounting and 0.100" lead pitch. Pin 1 is CS, pin 8 is VCC; all pins are electrically defined per SPI slave interface requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25040-10PI-2.7, M95040-DRMN3TP/K offers higher speed but removes hardware write lock, while BR24G04FJ-WE2 shifts to I²C with lower voltage support but eliminates both HOLD and dedicated WP-making AT25040-10PI-2.7 uniquely suited for robust, pin-compatible SPI systems requiring dual-layer protection and suspend capability.

Availability

AT25040-10PI-2.7 is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, automotive body electronics, and smart metering applications requiring stable component supply across extended product lifecycles.

Supply support for AT25040-10PI-2.7 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

Atmel Corporation, now part of Microchip Technology, designs high-reliability nonvolatile memory and microcontroller solutions for industrial, automotive, and consumer markets.

The AT250xx family delivers SPI-compatible serial EEPROMs optimized for low-voltage operation, robust data retention, and flexible write protection-targeting embedded systems needing trusted, pin-compatible memory upgrades.

FAQ

What is the maximum clock frequency supported by AT25040-10PI-2.7?

The AT25040-10PI-2.7 supports up to 3.0 MHz at VCC = 5.0V, and 2.1 MHz at VCC = 2.7V. These values are specified in the AC Characteristics table under fSCK parameter and reflect guaranteed timing margins for reliable SPI communication across the full industrial temperature range (−40°C to +85°C). Exceeding these frequencies may result in data corruption or command rejection.

Does AT25040-10PI-2.7 require an external erase cycle before writing?

No, AT25040-10PI-2.7 does not require a separate erase cycle. All write operations-including byte and page writes-are self-contained and automatically erase the target location prior to programming. This simplifies firmware design by eliminating erase timing management and enabling direct overwrite of any memory address without pre-clearing.

How does the HOLD pin function during an active SPI transaction on AT25040-10PI-2.7?

The HOLD pin on AT25040-10PI-2.7 suspends serial communication without resetting the internal address counter or command state. When asserted low while SCK is low, it places SO in high-impedance and ignores SI inputs until HOLD returns high (also while SCK is low). This allows the host MCU to service interrupts or switch peripherals mid-transfer without losing context-critical for deterministic real-time systems using AT25040-10PI-2.7.

Can AT25040-10PI-2.7 be used in automotive applications?

Yes, AT25040-10PI-2.7 is available in automotive-grade variants (e.g., AT25040-D10PI-2.7) qualified to AEC-Q100 Grade 3 (−40°C to +85°C) with enhanced reliability testing. While the standard AT25040-10PI-2.7 is rated for industrial temperature range, its 1 million endurance and 100-year data retention meet baseline automotive functional safety requirements for non-safety-critical configuration storage.

What happens if the WP pin is pulled low during a write operation on AT25040-10PI-2.7?

If the WP pin is pulled low during an ongoing write cycle on AT25040-10PI-2.7, the device immediately halts further programming and retains the partially written data. Subsequent attempts to write will be ignored until WP is returned high and a new WREN instruction is issued. This behavior ensures that power loss or noise-induced WP glitches do not corrupt memory contents beyond the last successfully committed byte.