Microchip Technology 24AA256T-E/SM

Overview

24AA256T-E/SM from Microchip Technology is a 256-Kbit I²C-compatible serial EEPROM with 32K × 8 organization, 1.7V–5.5V single-supply operation, 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 - deployed in embedded system configuration storage, sensor calibration data retention, and power-fail-safe parameter logging.

For engineers reviewing the 24AA256T-E/SM datasheet, 24AA256T-E/SM pinout, 24AA256T-E/SM application, or 24AA256T-E/SM equivalent, key selection criteria include I²C clock compatibility up to 400 kHz at ≥2.5V, 5 ms max page write time, 1 µA standby current, and SOIJ-8 package footprint with A0/A1/A2 address pins enabling multi-device bus topology.

Technical Context

The 24AA256T-E/SM implements a two-wire I²C interface with open-drain SDA/SCL requiring external pull-ups, and supports standard-mode (100 kHz) and fast-mode (400 kHz) timing per SMBus v2.0. Its internal address counter enables sequential reads across the full 0000h–7FFFh memory space, while cascading up to eight devices relies on hardwired A0–A2 chip-select bits.

Write operations are self-timed and internally managed: byte writes complete in ≤5 ms, and page writes (up to 64 bytes within a single 64-byte-aligned physical page) also require ≤5 ms. The device samples the WP pin at the Stop condition to enforce hardware-level write protection of the entire 256-Kbit array.

Key Specifications

Pinout & Package

24AA256T-E/SM is packaged in an 8-lead SOIJ (Small Outline J-bend) with 5.28 mm body width and 1.27 mm pitch. Pin 1 is marked with a beveled corner; pin numbering follows standard SOIC/SOIJ convention (counterclockwise from pin 1).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA256T-E/SM, the 24LC256-I/SN lacks 1.7V operation but matches its low-power profile, while the AT24C256-10PU-2.7 trades 9 µA higher standby current for 2.5× faster clock rate - making the 24AA256T-E/SM optimal for battery-critical, wide-VCC industrial nodes.

Availability

24AA256T-E/SM is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, automotive body control modules, and smart energy metering applications requiring stable component supply across extended product lifecycles.

Supply support for 24AA256T-E/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 microcontroller, analog, FPGA, and memory solutions, serving industrial, automotive, communications, and consumer markets with vertically integrated silicon and development tools.

The 24AA256T-E/SM belongs to Microchip's 24XX256 family of I²C EEPROMs, designed specifically for reliable, low-voltage, low-power nonvolatile data storage in space-constrained embedded systems.

FAQ

What is the maximum I²C clock frequency supported by the 24AA256T-E/SM?

The 24AA256T-E/SM supports up to 400 kHz I²C clock frequency when VCC ≥ 2.5V, and 100 kHz when VCC < 2.5V. This dual-speed capability ensures interoperability with both legacy and modern I²C masters while maintaining timing compliance across its full 1.7V–5.5V operating range. The 24AA256T-E/SM does not support 1 MHz operation - that capability is exclusive to the 24FC256 variant.

How does hardware write-protection work on the 24AA256T-E/SM?

Hardware write-protection on the 24AA256T-E/SM is controlled by the WP pin: when tied to VCC, all write operations (byte and page) are inhibited while read operations remain fully functional. The WP state is sampled only at the Stop condition of each write command, ensuring deterministic, glitch-immune protection that cannot be overridden by software or transient noise. This behavior is confirmed in DS20001203Y-page 11.

What package type is used for the 24AA256T-E/SM, and what are its key mechanical features?

The 24AA256T-E/SM uses an 8-lead SOIJ (Small Outline J-bend) package with 5.28 mm body width, 1.27 mm lead pitch, and J-lead geometry for enhanced solder joint reliability. Per DS20001203Y-page 16, the "SM" suffix explicitly denotes SOIJ packaging, distinguishing it from SOIC ("SN"), TSSOP ("ST"), or MSOP ("MS") variants. Pin 1 is identified by a beveled corner marking.

Can multiple 24AA256T-E/SM devices share the same I²C bus, and how is addressing managed?

Yes, up to eight 24AA256T-E/SM devices can share one I²C bus using hardwired A0, A1, and A2 pins to configure unique 3-bit chip addresses. Each device responds only when its A0–A2 combination matches the corresponding bits in the I²C control byte (1010 A2 A1 A0 R/W). This enables contiguous 2-Mbit expansion across devices, with software mapping A0–A2 to address bits A15–A17 as documented in DS20001203Y-page 10.

What is the guaranteed endurance and data retention specification for the 24AA256T-E/SM?

The 24AA256T-E/SM guarantees 1,000,000 erase/write cycles and greater than 200 years of data retention at +25°C, as specified in Table 1-2 (Param. No. 18) and DS20001203Y-page 5. These values are validated per JEDEC standards and apply to both byte and page write modes. Endurance is rated per page (64-byte boundary), not per byte, due to internal refresh behavior during partial-page writes.