Microchip Technology 24AA256T-I/MS

Overview

24AA256T-I/MS from Microchip Technology is a 256-Kbit I²C-compatible 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 >1 million erase/write cycles - deployed in embedded systems for parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 24AA256T-I/MS datasheet, 24AA256T-I/MS pinout, 24AA256T-I/MS application, or 24AA256T-I/MS equivalent, key selection criteria include low-voltage operation down to 1.7V, Schmitt-trigger noise immunity on SDA/SCL, self-timed 5 ms write cycle, and cascading support for up to eight devices on one I²C bus.

Technical Context

The 24AA256T-I/MS implements a two-wire I²C interface with open-drain SDA/SCL requiring external pull-ups, supporting standard (100 kHz), fast (400 kHz), and high-speed (1 MHz only for 24FC256) modes - but limited to 400 kHz at VCC ≥2.5V per device specification. Its internal address pointer enables sequential reads across the full 32K × 8 memory space, with automatic rollover from address 7FFFh to 0000h.

Write protection is controlled solely by the WP pin state (VSS = enabled, VCC = disabled), sampled at the Stop bit of each write command. The device uses on-chip charge pump for EEPROM programming and includes Schmitt-trigger inputs and output slope control to suppress ground bounce and noise-induced false transitions.

Key Specifications

Pinout & Package

8-lead MSOP (Micro Small Outline Package) with exposed pad option; pins A0 and A1 are not connected per datasheet Note under "Device Selection Table" and "PIN FUNCTION TABLE".

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC256T-I/MS and AT24C256-SSHL-T, the 24AA256T-I/MS uniquely supports true 1.7V operation and provides hardware-enforced write protection via dedicated WP pin - critical for battery-backed and safety-critical applications where voltage margin and data integrity are non-negotiable.

Availability

24AA256T-I/MS is available at Aetrix Electronics and suitable for smart meter calibration storage, automotive body control modules, and medical diagnostic sensor hubs requiring stable component supply across extended production lifecycles.

Supply support for 24AA256T-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 microcontroller, mixed-signal, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with high-reliability silicon and development tools.

The 24AA256T-I/MS belongs to Microchip's 24XX256 family of I²C serial EEPROMs, designed specifically for low-power, wide-voltage-range nonvolatile data storage in resource-constrained embedded systems.

FAQ

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

The 24AA256T-I/MS operates down to 1.7V, enabling direct integration with 1.8V logic families and battery-powered systems experiencing brownout conditions. This is confirmed in the Device Selection Table and Electrical Characteristics section of DS20001203Y, where VCC range is explicitly listed as 1.7V–5.5V for the 24AA256 variant. The 24AA256T-I/MS maintains full I²C functionality including 400 kHz clock support at this voltage.

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

Yes, the 24AA256T-I/MS supports multi-device addressing using the A2 pin, allowing up to two devices on the same I²C bus. Per the datasheet's "Device Selection Table" and "PIN FUNCTION TABLE", A0 and A1 are not connected in the MSOP package, leaving only A2 as a configurable chip-select bit. This yields two possible addresses (A2 = 0 or 1), enabling dual-device cascading for expanded storage without bus arbitration complexity.

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

Hardware write-protection on the 24AA256T-I/MS is controlled exclusively by the WP pin: tying WP to VCC disables all write operations (byte and page), while tying it to VSS enables them. As stated in Section 2.4 and Figure 1-1, the WP state is sampled at the Stop bit of each write command - toggling WP mid-cycle has no effect. This provides deterministic, pin-level security against accidental or malicious overwrites during power transitions.

What is the maximum page write size for the 24AA256T-I/MS?

The 24AA256T-I/MS supports a 64-byte page write buffer, meaning up to 64 bytes can be written in a single I²C transaction before the internal self-timed write cycle begins. This is specified in the Features list and Section 6.2. Page writes must remain within physical page boundaries (aligned to 64-byte offsets); crossing boundaries causes wraparound within the current page, not continuation into the next - requiring firmware-level boundary checking.

Is the 24AA256T-I/MS RoHS compliant and AEC-Q100 qualified?

The 24AA256T-I/MS is RoHS compliant as stated in the Features list, but it is not AEC-Q100 qualified. While the datasheet notes "Automotive AEC-Q100 Qualified" under Features, this applies only to specific variants (e.g., 24AA256T-E/MS with 'E' temp grade), not the 'I' (Industrial) grade 24AA256T-I/MS. The Device Selection Table confirms temperature range as Industrial (–40°C to +85°C), not Automotive, and no AEC-Q100 test data is referenced for this specific part number.