Microchip Technology 24AA256-E/MS

Overview

24AA256-E/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, 64-byte page write buffer, hardware write-protection via WP pin, and industrial temperature range (–40°C to +85°C). It enables nonvolatile data storage in space-constrained embedded systems requiring low-voltage operation and noise-immune bus interfacing.

For engineers reviewing the 24AA256-E/MS datasheet, 24AA256-E/MS pinout, 24AA256-E/MS application, or 24AA256-E/MS equivalent, key selection criteria include its 1.7V minimum supply, Schmitt-trigger SDA/SCL inputs for robust I²C communication in noisy environments, page write time ≤5 ms, 1 µA standby current, and support for up to eight cascaded devices on one bus using A0–A2 address lines - though A0 and A1 are unconnected in the MSOP variant.

Technical Context

The 24AA256-E/MS implements a two-wire I²C-compatible interface with open-drain SDA/SCL pins requiring external pull-ups, internal address pointer for sequential reads, and self-timed erase/write cycles. Its memory array is organized as 32K × 8 bits with 64-byte page boundaries, and it uses an internal high-voltage generator for EEPROM programming.

It supports byte and page write modes, current-address/random/sequential read operations, and acknowledge polling to detect write completion. The WP pin provides hardware-level write protection for the full 256-Kbit array, sampled at the Stop bit of each write command - a critical feature for firmware integrity in field-deployed systems.

Key Specifications

Pinout & Package

24AA256-E/MS is housed in an 8-lead MSOP (Mini Small Outline Package) with 0.65 mm lead pitch and exposed pad option. Pins A0 and A1 are not connected in this package variant; only A2, WP, SDA, SCL, VSS, and VCC are functional.

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-E/MS extends low-voltage operation to 1.7V and adds AEC-Q100 qualification; compared with AT24C256-MAHM-T, it delivers higher ESD immunity and automotive-grade reliability - making it optimal for safety-critical or battery-constrained applications.

Availability

24AA256-E/MS is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration, automotive body control units, and smart energy meters requiring stable component supply, long-term data retention, and automotive-grade reliability.

Supply support for 24AA256-E/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, serving automotive, industrial, consumer, and communications markets with vertically integrated silicon and software offerings.

The 24AA256 belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power nonvolatile storage in resource-constrained embedded systems where I²C interface simplicity and extended voltage operation are critical.

FAQ

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

The 24AA256-E/MS operates reliably down to 1.7V across its full industrial temperature range (–40°C to +85°C). This enables direct use with 1.8V logic families and single-cell lithium batteries without voltage boosting. Below 1.7V, read/write functionality is not guaranteed per the datasheet's absolute minimum specification.

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

Only two 24AA256-E/MS devices can share one I²C bus because the MSOP package has unconnected A0 and A1 pins - leaving only A2 as a configurable address bit. This yields two possible device addresses (1010xxx with A2 = 0 or 1), unlike the 8-device limit achievable with SOIC or PDIP variants that expose all three address pins.

Does the 24AA256-E/MS support 1 MHz I²C clock speed?

No, the 24AA256-E/MS supports up to 400 kHz I²C clock frequency. The 1 MHz capability is exclusive to the 24FC256 variant. Attempting 1 MHz operation with the 24AA256-E/MS will violate AC timing specifications (e.g., THIGH min = 600 ns), resulting in communication failures or data corruption.

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

If a page write command attempts to cross a 64-byte physical page boundary, the 24AA256-E/MS wraps the address back to the start of the current page instead of advancing to the next page. This overwrites previously loaded data in the buffer - a behavior documented in Section 6.3 of the datasheet. Application firmware must enforce page-aligned writes.

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

Yes, the 24AA256-E/MS is AEC-Q100 qualified for automotive use. The "E" suffix denotes Extended temperature grade (–40°C to +125°C), and the device meets stress testing requirements for automotive electronics, including thermal cycling, humidity bias, and ESD robustness (>4 kV HBM).