Microchip Technology AT25640-10PC-1.8

Overview

AT25640-10PC-1.8 from Atmel is a 64 Kbit (8192 × 8) SPI serial EEPROM optimized for low-voltage embedded systems, operating from 1.8 V to 3.6 V, supporting 32-byte page writes and block write protection (1/4, 1/2, or full array), with 5 ms typical write cycle time and 1 million endurance cycles - used in battery-powered IoT sensors and portable medical devices.

For engineers reviewing the AT25640-10PC-1.8 datasheet, AT25640-10PC-1.8 pinout, AT25640-10PC-1.8 application, or AT25640-10PC-1.8 equivalent, key selection criteria include 1.8 V operation margin, SPI Mode 0/3 compatibility, hardware/software write protection via WP pin and status register, and PDIP-8 package suitability for prototyping and industrial control interfaces.

Technical Context

The AT25640-10PC-1.8 implements a synchronous slave SPI interface with separate SI/SO lines, MSB-first data transfer, and chip-select–driven command protocol. It uses an 8-bit instruction register with op-codes for WREN, WRDI, RDSR, WRSR, READ, and WRITE, requiring explicit write-enable before programming.

Internal architecture includes nonvolatile status register bits (BP0/BP1/WPEN) controlling block protection granularity and hardware write enable/disable logic tied to the WP pin state. The HOLD pin suspends ongoing serial communication without resetting the sequence, enabling multi-device arbitration on shared buses.

Key Specifications

Pinout & Package

AT25640-10PC-1.8 is supplied in an 8-pin PDIP (Plastic Dual Inline Package), 0.300" wide, with through-hole mounting and standard 0.1" pin pitch - ideal for breadboard evaluation, legacy PCBs, and manual assembly in low-volume industrial modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95640-DRMN3TP/K and BR24G64FJ-WE2, AT25640-10PC-1.8 uniquely offers through-hole PDIP packaging for prototyping and legacy repair, guaranteed 1.8 V operation down to -40°C, and a mature, widely documented instruction set - making it optimal for industrial control upgrades and educational platforms where mechanical robustness and debug accessibility matter.

Availability

AT25640-10PC-1.8 is available at Aetrix Electronics and suitable for smart meter calibration storage, portable ECG device configuration, and industrial PLC I/O mapping requiring stable component supply across extended product lifecycles.

Supply support for AT25640-10PC-1.8 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) is a semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and wireless solutions for embedded systems.

The AT25xxx family was designed specifically for reliable, low-voltage serial data storage in industrial, medical, and consumer applications where SPI simplicity, write endurance, and long-term data retention are critical.

FAQ

What is the minimum supply voltage required for reliable operation of the AT25640-10PC-1.8?

The AT25640-10PC-1.8 is specified for reliable operation from 1.8 V to 3.6 V. Its absolute minimum functional supply is 1.8 V - below this, read/write functionality is not guaranteed per datasheet limits. At 1.8 V, AC timing parameters such as fSCK (max 0.5 MHz) and tWC (max 20 ms) apply, and ISB remains ≤0.2 µA. Operating below 1.8 V risks data corruption or command failure.

Does the AT25640-10PC-1.8 support SPI Mode 1 or Mode 2, or only Modes 0 and 3?

The AT25640-10PC-1.8 explicitly supports only SPI Modes 0 (CPOL = 0, CPHA = 0) and 3 (CPOL = 1, CPHA = 1), as confirmed in the Features section and timing diagrams. It does not support Mode 1 or Mode 2. Attempting Mode 1 or 2 will result in incorrect data sampling due to mismatched clock polarity and phase alignment with SI/SO transitions.

How does the HOLD pin function during an active write cycle in the AT25640-10PC-1.8?

The HOLD pin has no effect during an internal write cycle (tWC) in the AT25640-10PC-1.8. Once CS goes high to initiate programming, the device ignores all inputs including HOLD until the write completes. HOLD is only active during read or command sequences - it pauses serial communication by placing SO in high-impedance state while preserving the internal address counter.

Can the AT25640-10PC-1.8 be used interchangeably with the AT25640-10PC (5 V version) on the same PCB?

No - the AT25640-10PC-1.8 is not interchangeable with the 5 V AT25640-10PC on the same PCB. While pinout and package match, the -1.8 variant requires 1.8–3.6 V supply and exhibits different timing (e.g., 0.5 MHz max clock vs. 3.0 MHz), lower drive strength, and distinct DC characteristics. Substituting without adjusting VCC, pull-ups, and firmware timing risks communication failure or damage if 5 V is applied.

What happens if the WP pin is held low while the WPEN bit is '0' in the AT25640-10PC-1.8 status register?

When WPEN = 0, the WP pin is disabled regardless of its logic level - holding WP low has no protective effect. The device allows full write access to the status register and unprotected memory blocks. This configuration enables safe initial programming in systems where WP is hardwired to ground, as described in Table 5 of the datasheet. Only when WPEN = 1 does WP = low activate hardware protection.