Microchip Technology AT25640-10PC-2.7

Overview

AT25640-10PC-2.7 from Microchip Technology (formerly Atmel) is a 64 Kbit SPI serial EEPROM organized as 8192 × 8-bit memory, operating at 2.7V–5.5V supply, supporting 3.0 MHz clock rate at 5V, with 32-byte page write and hardware/software write protection. It serves as nonvolatile configuration storage in embedded controllers, power management units, and industrial sensor nodes requiring low-voltage reliability.

For engineers reviewing the AT25640-10PC-2.7 datasheet, AT25640-10PC-2.7 pinout, AT25640-10PC-2.7 application, or AT25640-10PC-2.7 equivalent, key selection criteria include VCC range compatibility (2.7–5.5V), 10 ms max write cycle time, block write protection granularity (1/4, 1/2, or full array), and 8-pin PDIP package suitability for through-hole prototyping and legacy board designs.

Technical Context

The AT25640-10PC-2.7 implements a synchronous SPI slave interface compliant with Modes 0 and 3, using separate SI/SO lines and CS/SCK/WP/HOLD control signals. Its internal architecture includes an 8-bit instruction register, nonvolatile status register (BP0/BP1/WPEN/WEN/RDY), and automatic address incrementing during sequential reads.

Write operations require explicit WREN instruction prior to WRITE or WRSR commands; self-timed internal write cycles (typ. 5 ms, max 10 ms) eliminate external timing constraints. Block protection is configured via status register bits BP0/BP1, enabling selective locking of memory segments without affecting unprotected regions.

Key Specifications

Pinout & Package

AT25640-10PC-2.7 uses an 8-pin PDIP (0.300" wide) package, compatible with standard through-hole sockets and manual soldering workflows. Pin 1 is marked with a notch or dot; leads are spaced on 0.100" pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95640-DW and 25AA640A-I/P, AT25640-10PC-2.7 offers unique HOLD pin support for real-time SPI pausing and fixed 2.7–5.5V operation ideal for stable 3.3V/5V hybrid systems, making it optimal for industrial controls where deterministic communication interruption is essential.

Availability

AT25640-10PC-2.7 is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration data retention, and consumer appliance user preference saving requiring stable component supply and long-term obsolescence management.

Supply support for AT25640-10PC-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

Microchip Technology is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with broad industrial and automotive qualification capabilities.

The AT25640-10PC-2.7 belongs to Microchip's legacy SPI EEPROM product line, designed for robust, low-power, pin-compatible configuration storage in cost-sensitive embedded systems where reliability and ease of integration are prioritized over ultra-high speed.

FAQ

What is the maximum clock frequency supported by AT25640-10PC-2.7 at 3.3V operation?

The AT25640-10PC-2.7 supports up to 2.1 MHz at 2.7–5.5V supply per AC characteristics table. At 3.3V, this translates to reliable operation at 2.1 MHz - sufficient for most configuration read/write tasks without compromising timing margins. The device maintains full functionality across its specified voltage range without derating, and the 2.1 MHz limit ensures setup/hold compliance under worst-case process/voltage/temperature conditions.

Does AT25640-10PC-2.7 support SPI Mode 1 or Mode 2?

No, AT25640-10PC-2.7 explicitly supports only SPI Modes 0 (CPOL=0, CPHA=0) and 3 (CPOL=1, CPHA=1) as stated in the 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. Host MCU SPI peripheral must be configured accordingly.

How is write protection configured on AT25640-10PC-2.7?

Write protection on AT25640-10PC-2.7 is configured via two mechanisms: (1) Hardware protection using the WP pin when WPEN bit = 1, and (2) Software protection using BP0/BP1 bits in the status register. The WRSR instruction sets BP0/BP1 to protect 0%, 25%, 50%, or 100% of the memory array. WP must be held low *and* WPEN=1 to activate hardware lock; otherwise, software protection alone applies.

What is the purpose of the HOLD pin on AT25640-10PC-2.7?

The HOLD pin on AT25640-10PC-2.7 allows temporary suspension of an ongoing SPI transaction without resetting the internal state or losing synchronization. When asserted low while SCK is low, it places SO in high-impedance and ignores SI inputs, enabling the host MCU to service interrupts or perform urgent tasks. Communication resumes upon deasserting HOLD while SCK remains low - preserving byte alignment and address counters.

Can AT25640-10PC-2.7 be used in place of AT25640-10PC without design changes?

Yes, AT25640-10PC-2.7 is a direct functional and pinout replacement for AT25640-10PC, differing only in supply voltage range: AT25640-10PC-2.7 operates from 2.7V–5.5V, while AT25640-10PC requires 4.5V–5.5V. All timing, instruction set, pin functions, and package dimensions are identical. No PCB or firmware modifications are needed when migrating to the -2.7 variant in systems with 3.3V or wider-rail supplies.