Microchip Technology AT25040-10PC-2.7

Overview

AT25040-10PC-2.7 from Atmel (now Microchip) is a 4-kbit SPI serial EEPROM organized as 512 × 8-bit memory, supporting 2.7V–5.5V operation, 2.1 MHz clock rate at 5V, and 8-byte page write mode. It features hardware write protection via WP pin, HOLD for communication suspension, and block-level write protection covering 1/4, 1/2, or full memory array - used in industrial sensor calibration storage and embedded system configuration retention.

For engineers reviewing the AT25040-10PC-2.7 datasheet, AT25040-10PC-2.7 pinout, AT25040-10PC-2.7 application, or AT25040-10PC-2.7 equivalent, key selection considerations include VCC range compatibility (2.7–5.5V), SOIC/PDIP package fit, SPI Mode 0/3 timing compliance, and 10 ms max self-timed write cycle duration.

Technical Context

The AT25040-10PC-2.7 operates as an SPI slave with separate SI/SO pins and MSB-first data transfer, requiring CS low to initiate commands including READ (0x03), WRITE (0x02), WREN (0x06), and RDSR (0x05). Its status register (BP1/BP0 bits) controls nonvolatile block protection, while WEN bit enables write latching independent of WP pin state.

Internal write cycles are fully self-timed (≤10 ms), eliminating external erase steps; during active writes, only RDSR is accepted - all other instructions are ignored until RDY=0. HOLD suspends SCK-synchronized communication without resetting address counters, enabling multi-master arbitration support.

Key Specifications

Pinout & Package

AT25040-10PC-2.7 is supplied in an 8-pin PDIP (package code 8P3) with 0.300" width, compatible with through-hole prototyping and legacy industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25040-10PC-2.7, M95040-DW omits HOLD capability and has divergent block protection implementation, while 25LC040A-I/P matches pinout and basic function but lacks automotive-grade temperature support - both require validation of status register interaction and WP timing behavior in target firmware.

Availability

AT25040-10PC-2.7 is available at Aetrix Electronics and suitable for industrial sensor calibration storage, embedded system configuration retention, and automotive ECU trim data storage requiring stable component supply across long production lifecycles.

Supply support for AT25040-10PC-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 communications markets.

The AT250xx family delivers SPI EEPROMs optimized for low-power, low-voltage embedded systems requiring robust data integrity, hardware/software write protection, and seamless integration with 8/16-bit MCUs.

FAQ

What is the maximum clock frequency supported by AT25040-10PC-2.7 at 3.3V operation?

The AT25040-10PC-2.7 supports up to 2.1 MHz at 5.0V, but AC characteristics specify 2.1 MHz also applies to the 2.7–5.5V range - meaning AT25040-10PC-2.7 operates reliably at 2.1 MHz across its full 2.7V–5.5V supply range, including 3.3V systems. This is confirmed in the AC Characteristics table where fSCK Min/Max entries for "2.7–5.5V" show 2.1 MHz maximum.

Does AT25040-10PC-2.7 require an external erase command before writing new data?

No, AT25040-10PC-2.7 does not require a separate erase command. All programming cycles are self-timed and automatically erase and rewrite the target byte or page. The device performs internal sector erasure as part of each WRITE or PAGE WRITE instruction - no pre-erase step is needed, simplifying firmware implementation.

How does the HOLD pin function during an ongoing AT25040-10PC-2.7 read sequence?

During an ongoing AT25040-10PC-2.7 read sequence, asserting HOLD low (while SCK is low) suspends communication without resetting the internal address counter. SO enters high-impedance state, and SI inputs are ignored. When HOLD returns high (with SCK still low), the read resumes from the exact next bit position - enabling deterministic pause/resume for time-critical host tasks.

Can AT25040-10PC-2.7 be used with SPI Mode 1 or Mode 2 interfaces?

No, AT25040-10PC-2.7 explicitly supports only SPI Modes 0 (CPOL=0, CPHA=0) and 3 (CPOL=1, CPHA=1), as stated in its Features section. It does not support Mode 1 (CPOL=0, CPHA=1) or Mode 2 (CPOL=1, CPHA=0); attempting to use unsupported modes will result in incorrect data sampling or communication failure.

What happens to the AT25040-10PC-2.7 status register after a power cycle?

After a power cycle, the AT25040-10PC-2.7 status register resets to default values: BP1=BP0=0 (no block protection), WEN=0 (write disabled), and RDY=0 (ready). The nonvolatile BP1/BP0 bits retain their programmed protection level across power cycles, but WEN is volatile and must be re-enabled via WREN instruction before any write operation.