Microchip Technology 24AA256T-E/MF

Overview

24AA256T-E/MF from Microchip Technology is a 256-Kbit I²C serial EEPROM with 32K × 8 organization, operating from 1.7V to 5.5V, supporting up to 400 kHz clock frequency, and rated for 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 system configuration storage, sensor calibration data retention, and power-fail-safe parameter backup.

For engineers reviewing the 24AA256T-E/MF datasheet, 24AA256T-E/MF pinout, 24AA256T-E/MF application, or 24AA256T-E/MF equivalent, key selection criteria include VCC min (1.7V), page write time (≤5 ms), endurance (1M cycles), data retention (>200 years), and I²C bus compatibility across voltage and speed grades - critical for low-power, space-constrained, and long-life designs.

Technical Context

The 24AA256T-E/MF 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 externally driven). Its EEPROM array uses charge-pump-based high-voltage generation for byte/page erase/write, with self-timed internal cycles eliminating external timing dependencies.

It supports three read modes (current address, random, sequential) and two write modes (byte and page), with acknowledge polling for write completion detection. Write protection is controlled solely by the WP pin state at Stop condition sampling - no software lock or register configuration required.

Key Specifications

Pinout & Package

24AA256T-E/MF is packaged in an 8-lead DFN (Dual Flat No-lead) with exposed thermal pad, footprint code MF per Microchip's packaging nomenclature. Pin 1 is marked by chamfered corner; package dimensions are 2.0 mm × 2.0 mm × 0.75 mm (L × W × H).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC256T-I/MF, the 24AA256T-E/MF enables true single-cell Li-ion or coin-cell operation; compared with AT24C256-10PU-2.7, it trades peak speed for broader voltage compatibility and guaranteed 1 µA standby across its full 1.7–5.5V range - making it optimal for ultra-low-power, wide-input-voltage, and automotive-qualified designs.

Availability

24AA256T-E/MF is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, automotive body control modules, and smart home gateway configuration requiring stable component supply across extended lifecycles.

Supply support for 24AA256T-E/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 microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design, manufacturing, and sales operations.

The 24AA256T-E/MF belongs to Microchip's 24XX256 family of I²C EEPROMs, engineered for robust, low-voltage, long-life nonvolatile storage in space-constrained and power-sensitive embedded systems.

FAQ

What is the minimum supply voltage required for reliable operation of the 24AA256T-E/MF?

The 24AA256T-E/MF operates reliably down to 1.7V across its full industrial temperature range (–40°C to +85°C). This enables direct integration with single-cell lithium batteries (nominal 3.0–3.7V, discharge down to ~2.5V) and coin cells (e.g., CR2032, 3.0V nominal, 2.0V end-of-life), eliminating need for voltage regulators in ultra-low-power designs. The 24AA256T-E/MF maintains full I²C functionality, including 400 kHz clock support, at all voltages from 1.7V to 5.5V.

How does the hardware write-protection (WP) pin function on the 24AA256T-E/MF?

The WP pin on the 24AA256T-E/MF is sampled only at the Stop condition of each I²C write command. When pulled high to VCC, it disables all write and erase operations - including byte writes, page writes, and page erases - while permitting unlimited read access. Toggling WP during an active write cycle has no effect; protection is enforced per-command, not continuously. This provides simple, glitch-immune, hardware-level data integrity without firmware involvement.

Can multiple 24AA256T-E/MF devices share the same I²C bus, and how is addressing managed?

Yes, up to eight 24AA256T-E/MF devices can share one I²C bus using hardwired A0, A1, and A2 pins to set unique 3-bit chip addresses (1010xxx binary prefix). Each device responds only to commands matching its physical address. For the MF-package DFN variant, all three address pins are functional. This enables scalable architectures such as multi-sensor nodes or modular control units without bus contention or software address arbitration.

What is the maximum write time for a full 64-byte page on the 24AA256T-E/MF?

The 24AA256T-E/MF guarantees a maximum page write time of 5 ms - this is the total elapsed time from Stop condition initiation to completion of internal programming, regardless of whether 1 or 64 bytes are written. During this period, the device does not acknowledge I²C commands (enabling ACK polling), and SDA remains high. This fixed, self-timed cycle simplifies host firmware design and ensures predictable worst-case latency for configuration updates.

Is the 24AA256T-E/MF qualified for automotive applications?

Yes, the 24AA256T-E/MF is AEC-Q100 qualified (Grade 3: –40°C to +85°C), meaning it has undergone rigorous stress testing for temperature cycling, humidity, ESD, and mechanical shock per automotive reliability standards. While not rated for under-hood high-temp Grade 1 (–40°C to +125°C), its qualification validates suitability for cabin, body control, infotainment, and ADAS subsystems where industrial-grade environmental robustness is required.