Microchip Technology 24AA256-I/SM

Overview

24AA256-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 buffering, 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 logging.

For engineers reviewing the 24AA256-I/SM datasheet, 24AA256-I/SM pinout, 24AA256-I/SM application, or 24AA256-I/SM equivalent, key selection considerations include its 1.7V minimum VCC, Schmitt-triggered SDA/SCL inputs for noise immunity, cascading support for up to eight devices on one I²C bus, and SOIJ-8 package compatibility with legacy through-hole and surface-mount PCB layouts.

Technical Context

The 24AA256-I/SM implements a two-wire I²C interface with standard 7-bit addressing (1010xxxR/W), where A0–A2 pins configure device address for multi-drop bus operation. Its internal architecture includes a 64-byte page latch, self-timed erase/write cycle, and HV generator for EEPROM cell programming - all managed by on-chip memory control logic without external timing components.

It supports byte and page write modes, random/sequential reads across the full 0000h–7FFFh address space, and acknowledge polling to detect write completion. The SOIJ-8 package (J-lead) used in the -I/SM variant features gull-wing leads compatible with wave and reflow soldering, with A0, A1, A2, VSS, VCC, SDA, SCL, and WP terminals fully functional per datasheet Table 2-1.

Key Specifications

Pinout & Package

24AA256-I/SM uses an 8-lead SOIJ (Small Outline J-bend) package with gull-wing leads, 3.90 mm body width, and JEDEC MS-012AC compliant footprint. Pin 1 is marked by a beveled corner or notch; lead pitch is 1.27 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC256-I/SN, the 24AA256-I/SM supports lower-voltage operation down to 1.7V and uses SOIJ-8 for compact surface-mount layouts; versus AT24C256-10PU-2.7, it offers broader VCC flexibility and automotive-qualified variants but trades off maximum clock speed for wider voltage tolerance.

Availability

24AA256-I/SM is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, and smart energy metering requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for 24AA256-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 microcontrollers, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24AA256 belongs to Microchip's serial EEPROM product line, engineered for ultra-low-power, high-reliability nonvolatile data storage in embedded systems where voltage flexibility, noise immunity, and long-term data integrity are critical.

FAQ

What is the minimum operating voltage for the 24AA256-I/SM?

The 24AA256-I/SM operates down to 1.7V, enabling direct integration with 1.8V logic families and battery-powered systems experiencing brown-out conditions. This specification is validated across the full industrial temperature range (−40°C to +85°C) and distinguishes it from the 24LC256, which requires ≥2.5V.

Does the 24AA256-I/SM support multi-device I²C bus configurations?

Yes, the 24AA256-I/SM supports cascading up to eight devices on a single I²C bus using its three hardware address pins (A0, A1, A2). Each device is assigned a unique 7-bit address (0x50–0x57) based on the logic levels applied to these pins, allowing scalable memory expansion without additional address decoding logic.

How does the write-protect (WP) pin function on the 24AA256-I/SM?

The WP pin on the 24AA256-I/SM is sampled at the Stop condition of each write command. When tied to VCC, it disables all write operations (including byte and page writes) while permitting unrestricted reads. When tied to VSS, full read/write access is enabled - providing hardware-level security against accidental or malicious firmware corruption.

What is the page write buffer size and maximum write time for the 24AA256-I/SM?

The 24AA256-I/SM features a 64-byte page write buffer, allowing up to 64 bytes to be loaded into the on-chip latch before initiating a self-timed internal write cycle. That cycle completes within 5 ms maximum, regardless of whether 1 or 64 bytes are written - optimizing bus efficiency and host processor utilization.

Is the 24AA256-I/SM qualified for automotive applications?

The base 24AA256-I/SM is rated for industrial temperature (−40°C to +85°C) and is not AEC-Q100 qualified. However, Microchip offers automotive-grade variants such as 24AA256-E/SM (extended temp) and 24AA256T-I/SM (with enhanced screening), which meet AEC-Q100 Grade 2 requirements for use in body electronics and infotainment subsystems.