Microchip Technology 25AA256-I/P

Overview

25AA256-I/P from Microchip Technology Inc. is a 256 Kbit (32,768 × 8) SPI Serial EEPROM with 1.8–5.5 V supply range, 64-byte page write capability, and industrial temperature rating (−40°C to +85°C). It features hardware write protection via WP pin, HOLD functionality for interrupt-safe bus suspension, and supports up to 10 MHz clock at 4.5–5.5 V. It is used in embedded systems for firmware parameter storage, calibration data retention, and configuration backup.

For engineers reviewing the 25AA256-I/P datasheet, 25AA256-I/P pinout, 25AA256-I/P application, or 25AA256-I/P equivalent, this page delivers verified electrical specs, SPI timing constraints, package-confirmed pin functions, endurance/reliability metrics, and real-world use cases aligned to Microchip's DS20001822H documentation.

Technical Context

The 25AA256-I/P implements a standard SPI Mode 0,0 (CPOL = 0, CPHA = 0) interface with separate SI/SO lines and active-low CS. Its internal architecture includes a 64-byte page latch, nonvolatile STATUS register with BP0/BP1 block protection bits, and HV generator for EEPROM cell programming.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate TWC (max 5 ms); read operations support sequential addressing with automatic address wrap-around. HOLD pin suspends ongoing transfers without resetting internal state, enabling deterministic interrupt handling in real-time microcontroller environments.

Key Specifications

Pinout & Package

25AA256-I/P is supplied in 8-lead PDIP (Plastic Dual In-Line Package) with 300-mil body width, RoHS-compliant matte tin plating, and standard through-hole mounting. Pin 1 is marked with a notch or dot; orientation follows JEDEC MS-001.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC256-I/P, the 25AA256-I/P extends voltage compatibility down to 1.8 V while maintaining identical pinout and SPI protocol - enabling drop-in use in ultra-low-power designs. Versus AT25DF256A-SSH-T, it trades raw speed for deterministic timing, hardware write protection, and seamless integration with legacy SPI peripherals.

Availability

25AA256-I/P is available at Aetrix Electronics and suitable for industrial PLC configuration storage, automotive ECU calibration data, and medical device usage logs requiring stable component supply across extended product lifecycles.

Supply support for 25AA256-I/P 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 25AA256 belongs to Microchip's serial EEPROM product line, engineered for reliable, low-power, SPI-compatible nonvolatile storage in industrial, automotive, and medical applications where data integrity and long-term retention are critical.

FAQ

What is the minimum supply voltage supported by the 25AA256-I/P?

The 25AA256-I/P operates down to 1.8 V, making it compatible with modern ultra-low-power microcontrollers and battery-powered systems. This is a key differentiator from the 25LC256 variant, which requires a minimum of 2.5 V. The 25AA256-I/P maintains full functionality-including 10 MHz operation at 4.5–5.5 V and 5 MHz at 2.5–4.5 V-across its entire 1.8–5.5 V range.

Does the 25AA256-I/P support page write operations, and what is the maximum size?

Yes, the 25AA256-I/P supports page write operations with a fixed 64-byte page size. Up to 64 bytes can be written in a single transaction, provided all addresses fall within the same physical page boundary (e.g., 0x0000–0x003F). Crossing a page boundary causes wraparound within the current page, so firmware must validate address alignment before initiating multi-byte writes.

How does the HOLD pin function during an active SPI transaction on the 25AA256-I/P?

The HOLD pin on the 25AA256-I/P pauses ongoing SPI communication without resetting internal state. When asserted low during SCK low time, SI/SO/SCK enter high-impedance and all inputs (except CS) are ignored. Upon release (HOLD high while SCK is low), transmission resumes from the exact bit position where it was suspended - enabling deterministic interrupt handling in time-critical MCU applications.

What write protection mechanisms are implemented in the 25AA256-I/P?

The 25AA256-I/P implements three-tiered write protection: (1) software-controlled STATUS register bits (BP0/BP1) for 0%/25%/50%/100% array locking; (2) hardware WP pin enabled only when WPEN bit = 1; and (3) power-on reset of the write enable latch. These layers ensure robust defense against accidental or malicious writes during boot, runtime, or brown-out conditions.

Is the 25AA256-I/P AEC-Q100 qualified, and for which temperature grade?

No - the 25AA256-I/P is rated for Industrial temperature range (−40°C to +85°C) and is not AEC-Q100 qualified. For automotive applications, Microchip offers the 25AA256-E/P variant (Extended grade, −40°C to +125°C), which carries AEC-Q100 qualification. The "I" suffix in 25AA256-I/P explicitly denotes Industrial grade, not automotive.