Microchip Technology 24LC256-E/MS

Overview

24LC256-E/MS from Microchip Technology is a 256-Kbit I²C serial EEPROM in an 8-lead MSOP package, operating from 2.5V to 5.5V with 400 kHz maximum 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 Schmitt-trigger inputs for noise immunity. Used in embedded systems for parameter storage, calibration data retention, and configuration memory.

For engineers reviewing the 24LC256-E/MS datasheet, 24LC256-E/MS pinout, 24LC256-E/MS application, or 24LC256-E/MS equivalent, key selection criteria include VCC min/max compliance, I²C timing at target bus speed, page write boundary handling, and MSOP thermal/mechanical fit in space-constrained PCB layouts.

Technical Context

The 24LC256-E/MS implements a two-wire I²C-compatible interface with fixed 4-bit control code (1010b) and 3-bit chip address (A2–A0), enabling up to eight devices on one bus-though only two are supported in MSOP due to unconnected A0/A1 pins. Its internal address counter supports sequential reads across the full 32K × 8 memory array (0000h–7FFFh).

Write operations are self-timed: byte writes complete in ≤5 ms; page writes (up to 64 bytes within a single 64-byte-aligned physical page) also require ≤5 ms. Acknowledge polling is supported to detect write completion without fixed delay, and the WP pin disables all writes when pulled high-sampled only at the Stop bit of each command.

Key Specifications

Pinout & Package

8-lead MSOP (Micro Small Outline Package), 3.0 mm × 3.0 mm body, 0.65 mm pitch, exposed pad optional (not electrically connected). Pins A0 and A1 are not connected - only A2 is functional for device addressing in this package.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA256-I/MS and AT24C256-MAHM-T, the 24LC256-E/MS provides deterministic 2.5V–5.5V operation and simplified addressing (A0/A1 unused), making it optimal for cost-sensitive industrial designs where low-voltage operation is unnecessary and board space restricts multi-device bus expansion.

Availability

24LC256-E/MS is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, automotive body control modules, and POS terminal configuration requiring stable component supply across extended production lifecycles.

Supply support for 24LC256-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, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24XX256 family-including 24LC256-E/MS-is designed for reliable, low-power nonvolatile data storage in embedded systems where I²C simplicity, long retention, and robust write endurance are critical.

FAQ

What is the minimum operating voltage for the 24LC256-E/MS?

The 24LC256-E/MS has a specified minimum VCC of 2.5V, unlike the 24AA256 (1.7V) or 24FC256 (1.7V). Operation below 2.5V is not guaranteed and may result in unreliable I²C communication or write failures. Always maintain VCC ≥2.5V for full specification compliance in the 24LC256-E/MS.

Does the 24LC256-E/MS support 1 MHz I²C clock speed?

No, the 24LC256-E/MS is rated for up to 400 kHz maximum clock frequency across its full 2.5V–5.5V VCC range. The 1 MHz capability is exclusive to the 24FC256 variant. Attempting 1 MHz operation on the 24LC256-E/MS will violate AC timing specifications and likely cause communication errors.

How many devices can be connected on the same I²C bus using the 24LC256-E/MS?

Only two 24LC256-E/MS devices can share one I²C bus because the MSOP package leaves A0 and A1 unconnected - only A2 is functional for chip addressing. This limits the address combinations to "00" and "01" (with A0/A1 hardwired internally to 0), yielding two unique addresses: 1010 0 0 0 R/W and 1010 0 0 1 R/W.

What happens if a page write crosses a 64-byte boundary on the 24LC256-E/MS?

If a page write command attempts to write across a 64-byte physical page boundary (e.g., starting at address 003Eh and writing 5 bytes), the address counter wraps within the current page - overwriting data at 0000h–0002h instead of continuing to 0040h–0042h. Software must enforce page-aligned writes or split commands to avoid unintended data loss.

Is the 24LC256-E/MS AEC-Q100 qualified?

Yes, the entire 24XX256 family-including the 24LC256-E/MS-is AEC-Q100 qualified for automotive applications. The "E" in the part number denotes Extended temperature grade (–40°C to +125°C), and the datasheet explicitly states AEC-Q100 qualification for the series, confirming suitability for automotive body electronics and infotainment systems.