Microchip Technology 24FC128T-I/SN

Overview

24FC128T-I/SN from Microchip Technology is a 128 Kbit (16K × 8) I²C-compatible serial EEPROM with 1 MHz maximum clock frequency at V_CC ≥ 2.5V, 1.7V–5.5V supply range, and industrial temperature rating (–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 system configuration storage, sensor calibration data retention, and firmware parameter backup.

For engineers reviewing the 24FC128T-I/SN datasheet, 24FC128T-I/SN pinout, 24FC128T-I/SN application, or 24FC128T-I/SN equivalent, key selection criteria include its 1 MHz I²C speed advantage over 24AA128/24LC128 variants, SOIC-8 (SN) package compatibility, industrial-grade reliability, and support for cascaded multi-device bus architectures up to eight units.

Technical Context

The 24FC128T-I/SN implements a two-wire I²C interface with master-controlled SCL/SDA timing, supporting standard (100 kHz), fast (400 kHz), and fast-plus (1 MHz) modes depending on V_CC. Its internal architecture includes a 64-byte page latch, address pointer with automatic increment, and HV generator for EEPROM cell programming.

Write operations are self-timed with ≤5 ms byte/page cycle duration; read operations support current-address, random, and sequential modes across the full 0x0000–0x3FFF address space. Hardware write protection is active when WP = V_CC, disabling all writes while preserving read functionality.

Key Specifications

Pinout & Package

24FC128T-I/SN uses an 8-lead SOIC-Narrow (SN) package per Microchip drawing C04-057-SN: 3.90 mm body width, 1.27 mm lead pitch, gull-wing leads, RoHS-compliant matte tin plating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA128T-I/SN, the 24FC128T-I/SN delivers 2.5× higher I²C throughput for dynamic parameter loading, while AT24C128-10PU-2.7 sacrifices low-voltage support and write protection - making 24FC128T-I/SN optimal for modern 1.8V/3.3V industrial designs demanding speed and security.

Availability

24FC128T-I/SN is available at Aetrix Electronics and suitable for industrial PLC configuration storage, automotive sensor calibration data retention, and medical device parameter backup requiring stable component supply across extended product lifecycles.

Supply support for 24FC128T-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, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24FC128T-I/SN belongs to Microchip's 24XX128 family of I²C EEPROMs, engineered specifically for robust, low-power nonvolatile data storage in space-constrained embedded systems operating across wide voltage and temperature ranges.

FAQ

What is the maximum I²C clock frequency supported by the 24FC128T-I/SN?

The 24FC128T-I/SN supports up to 1 MHz I²C clock frequency when V_CC is 2.5V or higher. At V_CC between 1.7V and 2.5V, the maximum clock frequency is 400 kHz. This dual-speed capability ensures compatibility with both legacy 400 kHz systems and high-throughput applications requiring faster configuration writes. The 24FC128T-I/SN datasheet specifies timing parameters including THIGH, TLOW, and TSU:DAT explicitly for both speed grades.

Does the 24FC128T-I/SN require external pull-up resistors on SDA and SCL lines?

Yes, the 24FC128T-I/SN 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 resistor to V_CC is recommended per Microchip's DS20001191T specification. The resistor value must be adjusted based on bus capacitance and desired rise time - lower values improve speed but increase power consumption. The 24FC128T-I/SN's Schmitt-trigger inputs tolerate slower edges, allowing flexibility in resistor selection.

How does hardware write protection work on the 24FC128T-I/SN?

Hardware write protection on the 24FC128T-I/SN is controlled by the WP (Write-Protect) pin: when WP is tied to V_CC, all write operations (byte and page) are inhibited while read operations remain fully functional. The pin state is sampled at the Stop bit of each write command. This feature prevents accidental overwrites during power transitions or firmware errors. Unlike software locks, WP protection remains active even if the host MCU fails - a critical safeguard in the 24FC128T-I/SN's industrial and automotive use cases.

Can multiple 24FC128T-I/SN devices share the same I²C bus?

Yes, up to eight 24FC128T-I/SN devices can share a single I²C bus using the A0, A1, and A2 address pins to configure unique 3-bit slave addresses. Each device's address is formed by the fixed '1010' control code followed by the logic levels on A0–A2. This allows a total addressable space of 1 Mbit (8 × 128 Kbit) without additional address decoding logic. The 24FC128T-I/SN's cascading capability simplifies modular system design where multiple subsystems require independent nonvolatile storage.

What is the page write buffer size and how does it affect write performance of the 24FC128T-I/SN?

The 24FC128T-I/SN has a 64-byte page write buffer, meaning up to 64 bytes can be loaded into the internal latch and written to memory in a single self-timed cycle (≤5 ms). This eliminates the need for 64 separate I²C transactions required in byte-write mode, reducing bus occupation by >98% and accelerating bulk writes. However, page writes must stay within physical page boundaries (0x0000–0x003F, 0x0040–0x007F, etc.); crossing boundaries causes wraparound - a constraint explicitly documented for the 24FC128T-I/SN.