Microchip Technology 24FC256-I/SN

Overview

24FC256-I/SN from Microchip Technology is a 256-Kbit (32K × 8) I²C-compatible serial EEPROM with 1.7V–5.5V single-supply operation, 1 MHz maximum clock frequency at V_CC ≥ 2.5V, and industrial temperature range (–40°C to +85°C). It features a 64-byte page write buffer, hardware write-protect (WP), Schmitt-trigger inputs, and >1 million erase/write cycles - deployed in embedded system configuration storage, sensor calibration data retention, and power-management parameter backup.

For engineers reviewing the 24FC256-I/SN datasheet, 24FC256-I/SN pinout, 24FC256-I/SN application, or 24FC256-I/SN equivalent, key selection criteria include its 1 MHz I²C speed advantage over 24AA256/24LC256 variants, SOIC-8 package compatibility, WP-enabled secure write control, and guaranteed 200-year data retention under industrial conditions.

Technical Context

The 24FC256-I/SN implements a two-wire I²C interface with fully compliant start/stop/acknowledge protocol, supporting up to eight devices on one bus via A0–A2 address pins. Its internal architecture includes a 64-byte page latch, HV generator for EEPROM programming, and memory control logic enabling byte- and page-write operations with self-timed erase/write cycles.

It uses Schmitt-trigger inputs on SDA/SCL for noise immunity and slope-controlled outputs to suppress ground bounce. Write protection is implemented via dedicated WP pin sampled at stop-bit assertion, and the device supports contiguous addressing expansion up to 2 Mbit across multiple units - though the SOIC-8 (SN) package retains full A0–A2 connectivity for full 8-device cascading.

Key Specifications

Pinout & Package

24FC256-I/SN is supplied in an 8-lead SOIC (Small Outline Integrated Circuit) package, designated by suffix "SN". Pin 1 is marked with a beveled corner or dot; the package is RoHS-compliant and lead-free.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA256-I/SN and AT24C256-10PU-2.7, the 24FC256-I/SN delivers superior throughput in time-critical configuration loads and extends system compatibility to 1.7V supply rails - making it optimal for next-generation ultra-low-power and mixed-voltage designs.

Availability

24FC256-I/SN is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body controllers, and smart energy meters requiring stable component supply, long-term lifecycle support, and guaranteed RoHS compliance.

Supply support for 24FC256-I/SN 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 automotive, industrial, consumer, and communications markets with vertically integrated silicon and development tools.

The 24FC256 belongs to Microchip's 24XX256 family of I²C EEPROMs, engineered for robust nonvolatile data storage in space-, power-, and cost-constrained embedded systems demanding high reliability and broad voltage operation.

FAQ

What is the maximum I²C clock frequency supported by the 24FC256-I/SN?

The 24FC256-I/SN supports up to 1 MHz I²C clock frequency when V_CC is 2.5V or higher. At V_CC < 2.5V, the maximum clock rate drops to 400 kHz. This dual-speed capability allows the 24FC256-I/SN to operate efficiently across both modern low-voltage systems and legacy 3.3V/5V platforms without sacrificing performance where voltage permits.

Does the 24FC256-I/SN require external pull-up resistors on SDA and SCL lines?

Yes, the 24FC256-I/SN requires external pull-up resistors on both SDA and SCL lines because its I²C interface uses open-drain outputs. For 1 MHz operation, a 2 kΩ pull-up to V_CC is recommended; for 400 kHz, 4.7 kΩ is typical. Proper pull-up strength ensures signal rise times meet AC specifications (≤300 ns for SDA/SCL at 1 MHz) and avoids bus contention.

How does the Write-Protect (WP) pin function on the 24FC256-I/SN?

The WP pin on the 24FC256-I/SN is sampled only at the STOP condition of each write command. When tied to V_CC, it disables all write operations (byte and page) while allowing unrestricted reads. When tied to V_SS, writes are enabled. The 24FC256-I/SN acknowledges write commands even with WP high, but no data is stored - providing safe, hardware-enforced protection against accidental overwrites.

Can multiple 24FC256-I/SN devices share the same I²C bus?

Yes, up to eight 24FC256-I/SN devices can share one I²C bus using the A0, A1, and A2 address pins to configure unique 3-bit chip addresses (0x50–0x57). Each device must have a distinct combination of A0–A2 tied to V_SS or V_CC. The 24FC256-I/SN's SOIC-8 package fully supports all three address pins, enabling full 8-device cascading without pin limitations.

What is the page write buffer size and how does it affect write efficiency?

The 24FC256-I/SN has a 64-byte page write buffer, allowing up to 64 bytes to be written in a single I²C transaction after issuing one START and address sequence, followed by STOP. This reduces protocol overhead versus individual byte writes - improving effective write throughput by up to 64×. However, software must ensure writes do not cross 64-byte physical page boundaries, or data will wrap within the current page.