Microchip Technology 24FC128T-I/SM

Overview

24FC128T-I/SM from Microchip Technology Inc. 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. Used in embedded system configuration storage, sensor calibration data retention, and firmware parameter backup.

For engineers reviewing the 24FC128T-I/SM datasheet, 24FC128T-I/SM pinout, 24FC128T-I/SM application, or 24FC128T-I/SM equivalent, key selection criteria include its 1 MHz I²C speed advantage over 24AA128/24LC128 variants, low 1 µA standby current, and SOIC-8 (SM) package compatibility with legacy board layouts.

Technical Context

The 24FC128T-I/SM implements a two-wire I²C slave interface with fixed 7-bit slave address prefix '1010' and user-configurable A2/A1/A0 bits enabling up to eight devices on one bus. Its internal architecture includes a 64-byte page latch, HV generator for EEPROM programming, and memory control logic supporting byte/page writes and random/sequential reads across the full 128 Kbit address space (0x0000–0x3FFF).

It uses CMOS EEPROM technology with self-timed erase/write cycles, Schmitt-trigger inputs on SDA/SCL for robust noise rejection, and slope-controlled outputs to suppress ground bounce. Write protection is implemented via dedicated WP pin sampled at Stop condition, and acknowledge polling is supported to detect write completion without fixed delay timing.

Key Specifications

Pinout & Package

24FC128T-I/SM is housed in an 8-lead SOIC package (JEDEC MS-012, body width 3.90 mm), marked "24FC128I/SM" per Microchip's standard marking convention. The package is RoHS-compliant, matte tin-plated, and suitable for reflow soldering per IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA128T-I/SM, the 24FC128T-I/SM delivers 2.5× faster configuration writes and broader voltage compatibility; versus AT24C128-10PU-2.7, it adds 1.7V operation and AEC-Q100 qualification for automotive use cases.

Availability

24FC128T-I/SM is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, and automotive body control modules requiring stable component supply across extended product lifecycles.

Supply support for 24FC128T-I/SM 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/SM belongs to Microchip's 24XX128 family of I²C EEPROMs, engineered for low-power, high-reliability nonvolatile storage in space-constrained embedded systems where voltage flexibility and noise immunity are critical.

FAQ

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

The 24FC128T-I/SM 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 across 1.8V, 3.3V, and 5V systems while maintaining optimal throughput where voltage permits. The 24FC128T-I/SM datasheet specifies THIGH and TLOW timing parameters accordingly for both ranges.

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

Yes, the 24FC128T-I/SM requires external pull-up resistors on both SDA and SCL lines because its I/O pins are open-drain. Recommended values are 2 kΩ for 1 MHz operation, 2.2 kΩ for 400 kHz, and 10 kΩ for 100 kHz-scaled to bus capacitance and rise-time requirements. The 24FC128T-I/SM's Schmitt-trigger inputs tolerate slower edges but maintain noise immunity within these constraints.

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

Hardware write-protection on the 24FC128T-I/SM is controlled by the WP pin: when tied to VCC, all write operations (byte/page) are inhibited while read access remains fully functional. The pin is sampled only at the Stop condition of each write command, so toggling WP mid-cycle has no effect. This ensures reliable protection against spurious writes during power transitions or ESD events without software dependency.

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

Yes, up to eight 24FC128T-I/SM devices can share a single I²C bus using the A2, A1, and A0 address pins to configure unique 3-bit chip select codes. Each device responds only to its assigned 7-bit slave address (1010xxxR/W). For the SOIC-8 (SM) package, all three address pins are functional-unlike MSOP variants where A0/A1 are NC-enabling full 8-device scalability in space-constrained designs.

What is the endurance specification for the 24FC128T-I/SM, and how is it measured?

The 24FC128T-I/SM guarantees 1,000,000 erase/write cycles per memory page (64 bytes), validated at 25°C and 5.5V per JEDEC standards. Endurance is specified per page-not per byte-because page-write operations refresh the entire 64-byte block. This reflects real-world usage where configuration data is updated in logical groups, and aligns with Microchip's Total Endurance™ model for lifetime estimation in specific applications.