Microchip Technology 24AA256T-E/MS

Overview

24AA256T-E/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, 1 µA standby current, and hardware write-protection via the WP pin. It delivers 64-byte page writes, >1 million erase/write cycles, and >200 years data retention for nonvolatile storage in low-power embedded systems.

For engineers reviewing the 24AA256T-E/MS datasheet, 24AA256T-E/MS pinout, 24AA256T-E/MS application, or 24AA256T-E/MS equivalent, key selection criteria include voltage range compatibility (1.7–5.5V), I²C timing compliance at 400 kHz, MSOP package footprint constraints, and hardware write-protect functionality for secure configuration storage.

Technical Context

The 24AA256T-E/MS implements a two-wire I²C interface with Schmitt-trigger inputs on SDA/SCL for noise immunity and slope-controlled outputs to suppress ground bounce. Its internal address pointer supports sequential reads across the full 32K × 8 memory space, with automatic rollover at address 7FFF.

It uses a self-timed erase/write cycle with a maximum 5 ms page write time and integrates a 64-byte page write buffer. The WP pin enables hardware-level write protection of the entire 256-Kbit array when pulled high, independent of software control.

Key Specifications

Pinout & Package

24AA256T-E/MS is housed in an 8-lead MSOP (Micro 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 serves as a chip-select input.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA256T-E/MS, the 24LC256-I/MS offers identical packaging and interface but lacks 1.7V operation, while the AT24C256-MAHM-T trades automotive qualification and endurance for lower unit cost in commercial-grade applications.

Availability

24AA256T-E/MS is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body controllers, medical diagnostic devices, and smart energy meters requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 24AA256T-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, specializing in embedded control and connectivity technologies for industrial, automotive, and consumer markets.

The 24AA256T-E/MS belongs to Microchip's 24XX256 serial EEPROM product line, designed specifically for reliable, low-voltage, I²C-based nonvolatile data storage in space- and power-constrained embedded systems.

FAQ

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

The 24AA256T-E/MS operates down to 1.7V, making it compatible with 1.8V logic families and single-cell lithium batteries. This low-voltage capability is confirmed in the Device Selection Table and Electrical Characteristics section of the DS20001203Y datasheet, where VCC range is explicitly specified as 1.7V–5.5V for the 24AA256 variant.

Does the 24AA256T-E/MS support I²C fast-mode (400 kHz) across its full voltage range?

Yes - the 24AA256T-E/MS supports up to 400 kHz I²C clock frequency for VCC ≥ 2.5V, and 100 kHz for VCC < 2.5V. This dual-speed behavior is documented in Table 1-2 (AC Characteristics) and the Device Selection Table, ensuring interoperability with both standard- and fast-mode I²C masters depending on supply conditions.

How many devices can be connected on the same I²C bus using the 24AA256T-E/MS?

Only two 24AA256T-E/MS devices can share the same I²C bus because its MSOP package has unconnected A0 and A1 pins, leaving only A2 as an active chip-select input. This limits address combinations to '0' and '1', as stated in Section 2.1 and Figure 5-1 of the datasheet.

What happens when the WP pin is tied to VCC on the 24AA256T-E/MS?

When WP is tied to VCC, all write operations (byte and page) to the 256-Kbit EEPROM array are inhibited, though read operations remain fully functional. The device acknowledges write commands but performs no internal programming, as verified in Section 6.3 and Figure 1-1 of the DS20001203Y datasheet.

Is the 24AA256T-E/MS qualified for automotive applications?

Yes - the "E" suffix in 24AA256T-E/MS denotes Extended temperature grade (–40°C to +125°C) and AEC-Q100 qualification, as confirmed in the Device Selection Table and Features list. This makes it suitable for under-hood and body-control applications where automotive reliability standards apply.