Microchip Technology 24AA256-E/P

Overview

24AA256-E/P from Microchip Technology is a 256-Kbit I²C-compatible serial EEPROM with 32K × 8 organization, 1.7V–5.5V single-supply operation, and industrial temperature range (–40°C to +85°C). It features 64-byte page write buffer, hardware write-protection via WP pin, and Schmitt-trigger inputs for noise immunity - deployed in embedded systems requiring nonvolatile parameter storage under low-voltage or space-constrained conditions.

For engineers reviewing the 24AA256-E/P datasheet, 24AA256-E/P pinout, 24AA256-E/P application, or 24AA256-E/P equivalent, key selection criteria include I²C clock compatibility up to 400 kHz at ≥2.5V, 1 µA standby current, 5 ms max page write time, and PDIP-8 package suitability for through-hole prototyping and legacy industrial control boards.

Technical Context

The 24AA256-E/P implements a two-wire I²C interface with open-drain SDA/SCL pins, internal address pointer for sequential reads, and cascaded addressing using A0–A2 inputs (hardwired or microcontroller-driven). Its EEPROM array supports byte and page writes with self-timed erase/write cycles and automatic address roll-over at 7FFFh boundary.

Write protection is enforced by sampling the WP pin state at the Stop bit of each write command; when tied to VCC, full array (0000h–7FFFh) is locked. Acknowledge polling enables host synchronization without fixed delays, leveraging the device's lack of ACK during internal write cycles.

Key Specifications

Pinout & Package

24AA256-E/P is supplied in an 8-lead PDIP (Plastic Dual In-line Package) with 0.300-inch body width, suitable for through-hole mounting on industrial PCBs and evaluation fixtures. Pin 1 is marked with a notch or dot; orientation follows JEDEC MS-001 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA256-E/P, the 24LC256-I/P sacrifices low-voltage operation for marginally lower unit cost, while the AT24C256-10PU-2.7 trades broader voltage tolerance for higher clock rate - making 24AA256-E/P optimal for battery-powered, wide-input-range, and industrial-grade deployments.

Availability

24AA256-E/P is available at Aetrix Electronics and suitable for smart metering, industrial PLC configuration, medical calibration storage, and automotive body control modules requiring stable component supply across extended product lifecycles.

Supply support for 24AA256-E/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 components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24AA256-E/P belongs to Microchip's 24XX256 family of I²C serial EEPROMs, engineered for robust, low-power nonvolatile data storage in industrial, automotive, and medical applications demanding high reliability and long-term data integrity.

FAQ

What is the maximum I²C clock frequency supported by the 24AA256-E/P?

The 24AA256-E/P supports up to 400 kHz I²C clock frequency when V_CC ≥ 2.5V. At V_CC < 2.5V (e.g., 1.8V operation), the maximum clock rate is limited to 100 kHz per Table 1-2. This dual-speed capability ensures interoperability across both legacy 100 kHz and modern 400 kHz I²C systems without redesign.

Does the 24AA256-E/P require external pull-up resistors on SDA and SCL lines?

Yes, the 24AA256-E/P requires external pull-up resistors on both SDA and SCL because these pins are open-drain. Recommended values are 10 kΩ for 100 kHz operation and 2 kΩ for 400 kHz, sized to meet rise time specifications (≤300 ns at V_CC ≥ 2.5V) while accounting for bus capacitance.

How does hardware write-protection work on the 24AA256-E/P?

Hardware write-protection on the 24AA256-E/P is controlled by the WP pin: when tied to VCC, all write operations (byte and page) are inhibited while read access remains fully functional. The WP state is sampled at the Stop bit of each write command, making it effective even during active transactions.

Can multiple 24AA256-E/P devices share the same I²C bus?

Yes, up to eight 24AA256-E/P devices can share one I²C bus using the A0, A1, and A2 address inputs to generate unique 3-bit chip addresses. Each device must have a distinct combination of A0–A2 tied to VSS or VCC; the base I²C address is 1010b followed by these bits and the R/W bit.

What is the purpose of the 64-byte page write buffer in the 24AA256-E/P?

The 64-byte page write buffer in the 24AA256-E/P allows up to 64 bytes to be loaded into on-chip latches before initiating a single self-timed write cycle. This reduces I²C bus traffic and host processor overhead by up to 64× compared to individual byte writes, accelerating bulk configuration updates in embedded systems.