Microchip Technology 24AA256-I/MF

Overview

24AA256-I/MF from Microchip Technology is a 256-Kbit I²C serial EEPROM with 32K × 8 organization, 1.7V–5.5V supply range, and industrial temperature rating (–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-used in embedded system configuration storage, sensor calibration data retention, and firmware parameter backup.

For engineers reviewing the 24AA256-I/MF datasheet, 24AA256-I/MF pinout, 24AA256-I/MF application, or 24AA256-I/MF equivalent, key selection criteria include I²C clock compatibility up to 400 kHz at V_CC ≥ 2.5V, 1 µA standby current, and cascading support for up to eight devices on one bus using A0/A1/A2 address pins.

Technical Context

The 24AA256-I/MF implements a two-wire I²C-compatible interface with open-drain SDA/SCL requiring external pull-ups. Its internal address counter enables sequential reads across the full 256-Kbit memory space, while page write logic buffers up to 64 bytes before initiating self-timed erase/write cycles.

Hardware write protection is controlled solely by the WP pin state at the Stop bit of each write command; no software lock or register configuration is involved. Device addressing uses a fixed 4-bit control code (1010b) plus three user-configurable chip-select bits (A2–A0), allowing up to eight devices on one bus-except in MSOP (max two) and SOT-23 (single-device only) packages.

Key Specifications

Pinout & Package

24AA256-I/MF is supplied in an 8-lead DFN package (3 mm × 2 mm, 0.5 mm pitch) with exposed thermal pad. Pin 1 is marked by a dot; the exposed pad may be connected to VSS or left floating per Microchip's packaging specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC256-I/MF, the 24AA256-I/MF enables 1.7V operation critical for battery-powered designs, while AT24C256-MAHM-T offers faster clocking but sacrifices automotive qualification and exact pin compatibility-making 24AA256-I/MF optimal for industrial and automotive I²C EEPROM needs requiring lowest-voltage robustness.

Availability

24AA256-I/MF is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, automotive body control modules, and smart energy meter data logging requiring stable component supply across extended lifecycle programs.

Supply support for 24AA256-I/MF 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 microcontroller, analog, FPGA, and memory solutions, serving industrial, automotive, and consumer markets with high-reliability semiconductor products.

The 24AA256 belongs to Microchip's serial EEPROM product line, designed specifically for low-power, I²C-based nonvolatile data storage in space-constrained embedded systems requiring guaranteed data integrity and long-term retention.

FAQ

What is the minimum supply voltage required for reliable operation of the 24AA256-I/MF?

The 24AA256-I/MF operates reliably down to 1.7V across its full industrial temperature range (–40°C to +85°C). This allows direct integration with 1.8V logic families and ensures functionality during brownout conditions in battery-powered systems. Operation below 1.7V is not characterized and may result in data corruption or communication failure.

How does the WP pin function on the 24AA256-I/MF, and when is it sampled?

The WP (Write-Protect) pin on the 24AA256-I/MF is sampled only at the Stop bit of each write command. When tied to VCC, it inhibits all write operations-including byte and page writes-while permitting unrestricted reads. Toggling WP during an active write cycle has no effect; protection state is latched at the precise moment the Stop condition is detected.

Can the 24AA256-I/MF be used in a multi-device I²C bus configuration, and how many devices can share one bus?

Yes, the 24AA256-I/MF supports multi-device I²C configurations using its A0, A1, and A2 address pins. With all three pins user-configurable, up to eight devices can share a single I²C bus. In the DFN package (which applies to 24AA256-I/MF), all three pins are functional and must be hardwired to VSS or VCC to assign a unique 3-bit chip address.

What is the maximum I²C clock frequency supported by the 24AA256-I/MF, and under what conditions?

The 24AA256-I/MF supports up to 400 kHz I²C clock frequency when V_CC is 2.5V or higher. At V_CC between 1.7V and 2.5V, the maximum clock frequency is limited to 100 kHz to ensure timing margin compliance. These limits are defined in the AC characteristics table and apply across the full industrial temperature range.

Does the 24AA256-I/MF require external components for I²C bus operation, and if so, what are they?

Yes, the 24AA256-I/MF requires external pull-up resistors on both SDA and SCL lines. Recommended values are 2 kΩ for 400 kHz operation and 10 kΩ for 100 kHz. A 0.1 µF ceramic decoupling capacitor is also required between VCC and VSS, placed within 10 mm of the device. No additional level-shifting or filtering components are needed for standard I²C interfacing.