Microchip Technology 24AA256-I/MS

Overview

24AA256-I/MS from Microchip Technology is a 256-Kbit I²C serial EEPROM in an 8-lead MSOP package, operating from 1.7V to 5.5V with 400 kHz max clock frequency 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-used for nonvolatile parameter storage in embedded control modules, sensor calibration data retention, and firmware configuration backup.

For engineers reviewing the 24AA256-I/MS datasheet, 24AA256-I/MS pinout, 24AA256-I/MS application, or 24AA256-I/MS equivalent, key selection criteria include low-voltage operation down to 1.7V, guaranteed 1 million erase/write cycles, 200-year data retention, I²C bus compatibility up to 400 kHz, and MSOP package footprint compatibility with space-constrained PCB layouts.

Technical Context

The 24AA256-I/MS implements a two-wire I²C-compatible interface with open-drain SDA/SCL pins requiring external pull-ups. Its internal address counter supports sequential reads across the full 32K × 8 memory array, and cascading up to eight devices (two for MSOP due to unconnected A0/A1 pins) is enabled via A2/A1/A0 chip-select bits.

Write operations are self-timed with maximum 5 ms byte/page cycle duration; acknowledge polling is supported to detect completion. Hardware write protection is active when WP = VCC, disabling all writes while permitting reads-critical for safeguarding factory-trimmed calibration constants or security keys.

Key Specifications

Pinout & Package

8-lead MSOP (Micro Small Outline Package) with 0.65 mm lead pitch; body dimensions 3.0 mm × 3.0 mm × 1.1 mm. Pins A0 and A1 are not connected per datasheet Note on page 7.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC256-I/MS, the 24AA256-I/MS enables true 1.8V system integration and offers 10× higher endurance-critical for field-updatable calibration data. Versus AT24C256-MAHM-T, it trades peak speed for proven long-term reliability in safety-critical storage.

Availability

24AA256-I/MS is available at Aetrix Electronics and suitable for smart meter calibration storage, industrial PLC configuration backup, and automotive body control unit settings requiring stable component supply across multi-year production programs.

Supply support for 24AA256-I/MS 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 belongs to Microchip's serial EEPROM product line, engineered for ultra-reliable, low-power nonvolatile data storage in industrial, automotive, and medical applications where data integrity and long-term retention are mandatory.

FAQ

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

The 24AA256-I/MS operates reliably down to 1.7V V_CC, making it compatible with 1.8V logic families without level shifters. This specification is validated across the full industrial temperature range (–40°C to +85°C) and applies to both read and write functions-including page writes and acknowledge polling-per DS20001203Y Section 1.0.

How many devices can be connected to the same I²C bus using the 24AA256-I/MS?

Up to two 24AA256-I/MS devices can share one I²C bus. Because the MSOP package has unconnected A0 and A1 pins (per datasheet page 7), only A2 is functional for chip addressing-yielding two possible I²C addresses (0x50 and 0x51). This differs from SOIC or TSSOP variants that support up to eight devices via A2/A1/A0.

Does the 24AA256-I/MS support 1 MHz I²C communication?

No-the 24AA256-I/MS supports up to 400 kHz I²C clock frequency at V_CC ≥ 2.5V (and 100 kHz below 2.5V). The 1 MHz capability is exclusive to the 24FC256 variant. Attempting 1 MHz operation on the 24AA256-I/MS will result in timing violations and unreliable ACK/NACK behavior per Table 1-2 AC Characteristics.

What happens if a page write crosses a 64-byte boundary on the 24AA256-I/MS?

If a page write command attempts to cross a 64-byte physical boundary (e.g., writing bytes 60–67), the 24AA256-I/MS wraps the excess data back to the start of the same page-overwriting previously written bytes 0–3. This behavior is documented in Section 6.3 and requires firmware to enforce page-aligned writes or split multi-page transfers manually.

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

The 24AA256-I/MS is rated for Industrial temperature (–40°C to +85°C) and is not AEC-Q100 qualified. For automotive use, Microchip offers the 24AA256-E/MS (Extended temp, –40°C to +125°C) or automotive-grade variants like the 24AA256T-I/MS with enhanced screening-neither of which is functionally identical to the 24AA256-I/MS in qualification scope.