Microchip Technology 24AA256T-I/SM

Overview

24AA256T-I/SM from Microchip Technology is a 256-Kbit I²C-compatible serial EEPROM with 32K × 8 organization, operating from 1.7V to 5.5V, supporting up to 400 kHz clock frequency at industrial temperature (−40°C to +85°C), and featuring hardware write-protection via the WP pin. It delivers 64-byte page write buffer, 1 µA standby current, and >1 million erase/write cycles - deployed in embedded system configuration storage, sensor calibration data retention, and power-fail-safe parameter backup.

For engineers reviewing the 24AA256T-I/SM datasheet, 24AA256T-I/SM pinout, 24AA256T-I/SM application, or 24AA256T-I/SM equivalent, key selection criteria include low-voltage operation down to 1.7V, I²C bus compatibility with Schmitt-trigger inputs for noise immunity, cascading support for up to eight devices on one bus, and factory-programmable options for pre-loaded firmware or calibration tables.

Technical Context

The 24AA256T-I/SM implements a two-wire I²C interface with open-drain SDA/SCL pins requiring external pull-ups, and uses internal address pointer logic to enable sequential, random, and current-address read modes across its full 256-Kbit memory space. Its architecture includes a 64-byte page latch buffer, self-timed erase/write cycle, and hardware-based write protection controlled by the WP pin sampled at Stop condition.

It supports device addressing via three configurable chip-select inputs (A0–A2), enabling up to eight devices on a shared bus (two for MSOP package); the /SM suffix denotes 8-lead SOIJ package with lead finish Matte Tin (Sn), rated for Industrial temperature range and RoHS compliance.

Key Specifications

Pinout & Package

24AA256T-I/SM is housed in an 8-lead SOIJ (Small Outline J-bend) package with Matte Tin (Sn) lead finish, 3.90 mm body width, and JEDEC MO-153 compliant footprint. Pin 1 is marked with a notch or dot; orientation follows standard SOIC/SOIJ conventions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC256T-I/SM, the 24AA256T-I/SM enables 1.7V operation critical for battery-powered systems, while AT24C256-10PU-2.7 offers higher bandwidth but sacrifices low-voltage flexibility and automotive qualification - making 24AA256T-I/SM optimal for robust, wide-supply industrial and medical designs.

Availability

24AA256T-I/SM is available at Aetrix Electronics and suitable for industrial sensor nodes, smart energy meters, medical diagnostic devices, and automotive body control modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for 24AA256T-I/SM 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, mixed-signal, analog, and Flash-IP solutions, serving industrial, automotive, consumer, and communications markets with vertically integrated silicon and development tools.

The 24AA256T-I/SM belongs to Microchip's 24XX256 family of I²C serial EEPROMs, designed specifically for low-power, high-reliability nonvolatile data storage in space-constrained embedded systems with stringent voltage and endurance requirements.

FAQ

What is the minimum operating voltage for the 24AA256T-I/SM?

The 24AA256T-I/SM operates down to 1.7V, enabling direct use with 1.8V logic families and battery-powered systems where supply voltage may dip below 2.5V. This distinguishes it from the 24LC256 variant, which requires a minimum of 2.5V. The 24AA256T-I/SM maintains full I²C functionality, including 400 kHz clock support, across the entire 1.7V–5.5V range.

Does the 24AA256T-I/SM support multiple devices on the same I²C bus?

Yes, the 24AA256T-I/SM supports up to eight devices on a single I²C bus using its three hardware address pins (A0, A1, A2). Each pin is hardwired to VSS or VCC to configure a unique 3-bit chip address. For the SOIJ package (denoted by /SM), all three pins are functional - unlike the MSOP variant where A0 and A1 are NC. This enables scalable memory expansion up to 2 Mbit in cascaded configurations.

How does hardware write-protection work on the 24AA256T-I/SM?

The WP (Write-Protect) pin on the 24AA256T-I/SM is sampled only at the Stop condition of each write command. When tied to VCC, it disables all write operations (byte and page) while allowing unrestricted reads. This hardware lock is immune to software crashes or bus contention, ensuring critical configuration data remains unaltered - a key requirement for medical and industrial safety-critical applications using the 24AA256T-I/SM.

What is the maximum page write size supported by the 24AA256T-I/SM?

The 24AA256T-I/SM features a 64-byte page write buffer, allowing up to 64 bytes to be written in a single I²C transaction after issuing one Start condition and before the final Stop condition. This reduces bus overhead significantly versus byte-write mode. However, page writes must remain within physical page boundaries (0x0000–0x003F, 0x0040–0x007F, etc.); crossing boundaries causes wraparound, not automatic page advancement.

Is the 24AA256T-I/SM qualified for automotive applications?

The 24AA256T-I/SM itself is specified for Industrial temperature range (−40°C to +85°C) and is not individually AEC-Q100 certified. However, it belongs to the broader 24XX256 family, some variants of which (e.g., 24AA256-E/SM) are AEC-Q100 qualified. For automotive body control modules, designers should verify qualification status per specific part number and consult Microchip's automotive product documentation before deployment.