Microchip Technology 24AA256-E/SM

Overview

24AA256-E/SM from Microchip Technology is a 256-Kbit I²C serial EEPROM with 32K × 8 organization, 1.7V–5.5V single-supply operation, hardware write-protection via WP pin, and 64-byte page write buffer. It supports up to eight devices on one bus using A0–A2 address inputs and delivers 400 kHz I²C communication at V_CC ≥ 2.5V - used in industrial sensor calibration storage and embedded system configuration retention.

For engineers reviewing the 24AA256-E/SM datasheet, 24AA256-E/SM pinout, 24AA256-E/SM application, or 24AA256-E/SM equivalent, key selection criteria include low-voltage operation down to 1.7V, 1 µA standby current, Schmitt-trigger noise immunity on SDA/SCL, and guaranteed 1 million write cycles with >200-year data retention.

Technical Context

The 24AA256-E/SM implements a two-wire I²C-compatible interface with open-drain SDA/SCL requiring external pull-ups, and uses internal address pointer logic for sequential reads across the full 0000h–7FFFh memory space. Its write-protect function is sampled at the Stop bit, and page writes are constrained to physical 64-byte boundaries without automatic wraparound to adjacent pages.

It features Schmitt-trigger inputs (V_HYS = 0.05V_CC) and slope-controlled outputs to suppress ground bounce, enabling reliable operation in electrically noisy industrial environments. Acknowledge polling is supported to detect write-cycle completion without fixed timing delays.

Key Specifications

Pinout & Package

24AA256-E/SM is supplied in an 8-lead SOIJ (Small Outline J-bend) package with 5.28 mm body width and JEDEC MS-012AC standard footprint. Pin 1 is marked by notch or bevel; leads are matte tin-plated.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC256-I/SN and AT24C256-10PU-2.7, the 24AA256-E/SM uniquely supports 1.7V operation and 1M write cycles - making it optimal for battery-powered, low-voltage, and high-reliability embedded systems demanding extended data retention.

Availability

24AA256-E/SM is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, automotive body control modules, and smart energy metering requiring stable component supply across extended temperature ranges.

Supply support for 24AA256-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, mixed-signal, analog, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with vertically integrated silicon and development tools.

The 24AA256-E/SM belongs to Microchip's 24XX256 family of I²C EEPROMs, designed specifically for low-power, wide-voltage-range nonvolatile storage in space- and energy-constrained embedded systems.

FAQ

What is the maximum I²C clock frequency supported by the 24AA256-E/SM?

The 24AA256-E/SM supports up to 400 kHz I²C clock frequency when V_CC ≥ 2.5V. At V_CC < 2.5V (e.g., 1.8V operation), the maximum clock frequency is limited to 100 kHz per DS20001203Y specification. This dual-speed capability ensures compatibility across both legacy and ultra-low-power designs without external clock dividers.

How does the hardware write-protect (WP) pin function on the 24AA256-E/SM?

The WP pin on the 24AA256-E/SM is sampled at the Stop condition of each write command. When tied to V_CC, it disables all write operations (byte and page) while permitting unlimited reads. When tied to V_SS, writes are enabled. This hardwired protection prevents accidental overwrites during power transients or firmware faults - a critical feature for preserving calibration data in the 24AA256-E/SM.

Can the 24AA256-E/SM perform sequential reads across the entire 256-Kbit memory space?

Yes, the 24AA256-E/SM supports sequential reads across its full 0000h–7FFFh address range. After issuing a Start condition and control byte with R/W = 1, the device transmits data bytes continuously; the internal address pointer auto-increments and rolls over from 7FFFh to 0000h. Each byte is acknowledged by the host until the final byte, after which a No-Ack + Stop terminates the 24AA256-E/SM transmission.

What is the page write buffer size of the 24AA256-E/SM, and how does it affect write performance?

The 24AA256-E/SM features a 64-byte page write buffer. This allows up to 64 bytes to be loaded into the buffer and written to memory in a single self-timed cycle (≤5 ms), reducing I²C transaction overhead significantly versus byte-write mode. However, page writes cannot cross 64-byte physical boundaries - software must align addresses to prevent data wraparound within the same page.

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

No, the 24AA256-E/SM is specified for Industrial (–40°C to +85°C) and Extended (–40°C to +125°C) temperature ranges but is not AEC-Q100 qualified. For automotive use, Microchip offers the 24AA256T-I/SN variant (with 'T' suffix) which meets AEC-Q100 Grade 2 requirements. The 24AA256-E/SM remains suitable for industrial and medical applications requiring extended temperature operation without formal automotive certification.