Microchip Technology 24LC256-E/P

Overview

24LC256-E/P from Microchip Technology is a 256-Kbit I²C-compatible serial EEPROM in an 8-lead PDIP package, operating from 2.5V to 5.5V with 400 kHz max clock frequency and industrial temperature range (–40°C to +85°C). It features 64-byte page write buffering, hardware write-protection via WP pin, and >1 million erase/write cycles. It is used for nonvolatile parameter storage in embedded controllers and sensor calibration modules.

For engineers reviewing the 24LC256-E/P datasheet, 24LC256-E/P pinout, 24LC256-E/P application, or 24LC256-E/P equivalent, key selection criteria include VCC min/max compliance, I²C timing at target bus speed, page write boundary handling, and WP pin logic behavior during power-up sequencing.

Technical Context

The 24LC256-E/P 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 current-address, random, and sequential reads across the full 32K × 8 memory array.

Write operations are self-timed and support byte or page mode (up to 64 bytes), with automatic wraparound within physical page boundaries. The device samples the WP pin at the Stop bit to enable/disable writes, and uses acknowledge polling to signal write completion without fixed timeout delays.

Key Specifications

Pinout & Package

24LC256-E/P is supplied in an 8-lead plastic dual in-line package (PDIP), 300 mil width, with through-hole mounting and industry-standard pin spacing. Pin 1 is marked by a notch or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA256-I/P, the 24LC256-E/P avoids over-specifying low-voltage capability while maintaining identical industrial temperature rating and package. Against AT24C256-PU, it guarantees Microchip's documented timing margins and WP behavior under transient VCC conditions.

Availability

24LC256-E/P is available at Aetrix Electronics and suitable for industrial sensor calibration, embedded system configuration, and automotive body control modules requiring stable component supply and long-term lifecycle support.

Supply support for 24LC256-E/P 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 manufacturing and support infrastructure.

The 24LC256 belongs to Microchip's 24XX256 family of I²C serial EEPROMs, designed specifically for robust, low-power nonvolatile data storage in space-constrained embedded systems across industrial and automotive applications.

FAQ

What is the minimum VCC required for reliable operation of the 24LC256-E/P?

The 24LC256-E/P requires a minimum VCC of 2.5V for guaranteed operation across its full industrial temperature range (–40°C to +85°C). Operation below 2.5V is not specified and may result in unpredictable write behavior or communication failure. This distinguishes it from the 24AA256 variant, which supports down to 1.7V.

Does the 24LC256-E/P support 1 MHz I²C clock frequency?

No, the 24LC256-E/P is rated for a maximum I²C clock frequency of 400 kHz. It does not support 1 MHz fast-mode operation. For 1 MHz compatibility, the 24FC256 variant must be used. Attempting 1 MHz communication with the 24LC256-E/P may cause timing violations and data corruption.

How does the WP pin function on the 24LC256-E/P during power-up?

The WP pin on the 24LC256-E/P is sampled at the Stop bit of each write command-not continuously-so its state during power-up has no effect on initial operation. Write protection is only enforced when WP is held high at the moment the Stop condition is detected. During power ramp, WP should be stabilized before issuing write commands.

Can multiple 24LC256-E/P devices share the same I²C bus?

Yes, up to eight 24LC256-E/P devices can be cascaded on a single I²C bus using the A0, A1, and A2 address pins to configure unique 3-bit chip select codes. Each device must have a distinct combination of these pins tied to VSS or VCC to avoid address collisions during communication.

What is the maximum number of bytes that can be written in a single page write operation for the 24LC256-E/P?

The 24LC256-E/P supports a maximum of 64 bytes per page write operation. Writing more than 64 bytes before issuing a Stop condition causes the address counter to roll over within the same physical page, overwriting previously loaded data. Software must enforce page boundaries to prevent unintended data loss.