Microchip Technology 24LC256T-E/MS

Overview

24LC256T-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 - deployed in embedded systems for parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 24LC256T-E/MS datasheet, 24LC256T-E/MS pinout, 24LC256T-E/MS application, or 24LC256T-E/MS equivalent, key selection criteria include VCC compatibility (2.5–5.5V), I²C timing compliance at 400 kHz, MSOP package footprint constraints, and hardware write-protect behavior during power-up sequencing.

Technical Context

The 24LC256T-E/MS implements a two-wire I²C interface with open-drain SDA/SCL requiring external pull-ups, supports up to eight devices on one bus via A0–A2 address bits (though A0/A1 are NC in MSOP), and uses internal address pointer logic for sequential reads across the full 32K × 8 memory array. Its self-timed erase/write cycle eliminates external timing control.

It integrates Schmitt-trigger inputs on SDA/SCL for robust noise suppression, slope-controlled outputs to minimize ground bounce, and a 64-byte page buffer enabling efficient bulk writes without host-side buffering. Write protection is asserted when WP = VCC, disabling all write operations while preserving read functionality.

Key Specifications

Pinout & Package

Package: 8-lead MSOP (3.0 mm × 3.0 mm, 0.65 mm pitch). Pins A0 and A1 are not connected (NC) per datasheet Note on page 7; A2, WP, SDA, SCL, VCC, and VSS are functional.

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 24LC256T-E/MS delivers optimized cost-performance balance for stable 3.3V/5V industrial applications requiring guaranteed 400 kHz timing, hardware write-protect, and AEC-Q100-aligned reliability - without over-specifying voltage range or speed.

Availability

24LC256T-E/MS is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, and automotive body control modules requiring stable component supply, long-term data retention, and RoHS-compliant packaging.

Supply support for 24LC256T-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, FPGA, and memory solutions, serving industrial, automotive, and consumer markets with vertically integrated design and manufacturing.

The 24LC256T-E/MS belongs to Microchip's serial EEPROM product line, engineered for reliable, low-power nonvolatile storage in resource-constrained embedded systems where I²C interface simplicity and hardware write protection are essential.

FAQ

What is the operating voltage range of the 24LC256T-E/MS?

The 24LC256T-E/MS operates from 2.5V to 5.5V. Unlike the 24AA256 variant, it does not support voltages below 2.5V. This makes it suitable for stable 3.3V and 5V systems but excludes ultra-low-voltage battery applications. The specified range ensures reliable I²C communication and EEPROM write functionality across its full industrial temperature range.

Does the 24LC256T-E/MS support multiple devices on the same I²C bus?

Yes, the 24LC256T-E/MS supports multi-device addressing using the A2 pin (A0 and A1 are NC in MSOP). With A2 configurable as 0 or 1, up to two 24LC256T-E/MS devices can share one I²C bus. The base I²C address is 1010b, with A2 as the MSB of the chip select field, yielding addresses 0x50 and 0x51 when A2 = 0 or 1 respectively.

How does hardware write-protection work on the 24LC256T-E/MS?

Hardware write-protection on the 24LC256T-E/MS is controlled by the WP pin: when tied to VCC, all write operations (byte and page) are inhibited while reads remain fully functional. The WP state is sampled at the Stop condition of each write command, so toggling WP mid-cycle has no effect. This provides deterministic, power-fail-safe protection against unintended writes.

What is the maximum I²C clock frequency supported by the 24LC256T-E/MS?

The 24LC256T-E/MS supports up to 400 kHz I²C clock frequency at VCC ≥ 2.5V. It is not rated for 1 MHz operation like the 24FC256 variant. Timing parameters such as THIGH (≥600 ns), TLOW (≥1300 ns), and TR/TF (≤300 ns) must be met to ensure reliable communication at this speed, requiring appropriate pull-up resistor selection and PCB layout.

Can the 24LC256T-E/MS perform sequential reads across its entire memory array?

Yes, the 24LC256T-E/MS supports sequential reads across the full 32K × 8 memory space. After a Start condition and valid address setup, the device auto-increments its internal address pointer with each byte read. Upon reaching address 0x7FFF, the pointer rolls over to 0x0000, enabling continuous streaming without host-side address management - ideal for firmware image verification or bulk parameter dumps.