Microchip Technology 24FC256-I/P

Overview

24FC256-I/P 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-protection via WP pin, and Schmitt-trigger inputs for noise immunity - deployed in embedded system configuration storage, sensor calibration data retention, and power-fail-safe parameter logging.

For engineers reviewing the 24FC256-I/P datasheet, 24FC256-I/P pinout, 24FC256-I/P application, or 24FC256-I/P equivalent, key selection criteria include its 1 MHz I²C speed capability (vs. 400 kHz for 24AA256), low 1 µA standby current, 5 ms max page write time, and PDIP-8 package compatibility with legacy through-hole designs.

Technical Context

The 24FC256-I/P implements a two-wire I²C interface with fully compliant start/stop condition generation, acknowledge polling support, and cascading up to eight devices using 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 supports three read modes - current address, random, and sequential - with automatic address pointer roll-over at 0x7FFF. The device uses open-drain SDA/SCL with external pull-ups and incorporates slope control on outputs to suppress ground bounce, while Schmitt-trigger inputs ensure robustness against bus noise across its full 1.7V–5.5V operating range.

Key Specifications

Pinout & Package

24FC256-I/P is supplied in an 8-lead PDIP (Plastic Dual In-line Package) with 0.300-inch body width, compatible with standard through-hole PCB assembly and socketing. Pin 1 is marked by a notch or dot; orientation follows JEDEC MS-001 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA256-I/P and AT24C256-PU, the 24FC256-I/P delivers higher I²C throughput and broader voltage flexibility, making it optimal for next-generation low-power embedded systems requiring fast, reliable nonvolatile storage without layout changes.

Availability

24FC256-I/P is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, and smart energy metering requiring stable component supply across extended product lifecycles.

Supply support for 24FC256-I/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 microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24FC256 belongs to Microchip's 24XX256 family of I²C serial EEPROMs, engineered for ultra-low-power, high-reliability nonvolatile data storage in space-constrained and thermally demanding embedded applications.

FAQ

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

The 24FC256-I/P 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 seamless integration into both legacy 400 kHz systems and newer high-throughput designs - a key differentiator versus the 24AA256-I/P, which is limited to 400 kHz across its entire voltage range. The 24FC256-I/P datasheet confirms this behavior in Table 1-2.

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

Yes, the 24FC256-I/P requires external pull-up resistors on both SDA and SCL lines because these pins are open-drain. For 1 MHz operation, a 2 kΩ pull-up to V_CC is recommended; for 400 kHz, 2.2 kΩ is typical. The value must be selected based on bus capacitance and desired rise time - the 24FC256-I/P's output slope control helps maintain signal integrity even with moderate bus loads, but proper termination remains essential for reliable I²C communication.

How does the WP pin function on the 24FC256-I/P?

The WP (Write-Protect) pin on the 24FC256-I/P is an active-high hardware lock: when tied to V_CC, it disables all write operations (byte and page) while permitting unlimited reads. When tied to V_SS, full read/write access is enabled. The pin is sampled at the Stop bit of each write command - toggling WP mid-cycle has no effect. This feature is critical for safeguarding calibration data or firmware parameters in the 24FC256-I/P during power-up sequences or software resets.

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

Yes, up to eight 24FC256-I/P devices can operate on a single I²C bus using the A0, A1, and A2 address pins to configure unique 3-bit chip addresses. Each pin must be hardwired to either V_SS or V_CC to set its logic level. The 24FC256-I/P's PDIP-8 package exposes all three address pins, enabling full 8-device addressing - unlike MSOP or SOT-23 variants where some address pins are NC. This scalability supports modular system designs with distributed nonvolatile storage.

What is the page write time specification for the 24FC256-I/P?

The 24FC256-I/P specifies a maximum page write time of 5 ms for both byte and page writes. This is the duration of the internal self-timed erase/write cycle initiated after the host issues a Stop condition. During this period, the device does not acknowledge I²C commands - a behavior leveraged by acknowledge polling to detect completion. This 5 ms value is consistent across all operating voltages and temperatures, and is confirmed in Section 1.0 Electrical Characteristics (Table 1-2, Parameter TWC) of the 24FC256-I/P datasheet.