Microchip Technology 24FC128T-I/MS

Overview

24FC128T-I/MS 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, 1.7–5.5V supply range, and industrial temperature operation (–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/MS datasheet, 24FC128T-I/MS pinout, 24FC128T-I/MS application, or 24FC128T-I/MS equivalent, key selection criteria include I²C speed compatibility (1 MHz), low-voltage operation down to 1.7V, page write efficiency, endurance (>1 million cycles), and MSOP-8 package footprint constraints.

Technical Context

The 24FC128T-I/MS implements a two-wire I²C slave interface with fixed 7-bit address prefix '1010', three user-configurable chip-select bits (A2/A1/A0), and R/W bit control. Its internal architecture includes a 64-byte page latch, HV generator for EEPROM programming, and memory control logic supporting byte/page writes and current/random/sequential reads up to the 128K boundary.

It supports cascading up to eight devices on one bus (two for MSOP due to A0/A1 no-connect), uses open-drain SDA/SCL with external pull-ups, and incorporates slope control and Schmitt-trigger inputs to suppress ground bounce and noise spikes. Write protection is hardware-enforced via dedicated WP pin sampled at Stop condition.

Key Specifications

Pinout & Package

24FC128T-I/MS is housed in an 8-lead MSOP (Mini Small Outline Package) with 3.0 mm × 3.0 mm body, 0.65 mm lead pitch, and exposed pad (optional V_SS connection). Pins A0 and A1 are not connected in this package variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24FC128T-I/MS, the 24AA128T-I/MS trades 1 MHz performance for broader vendor support and slightly lower unit cost, while the AT24C128-MSH-T offers cross-manufacturer compatibility at the expense of noise immunity and write-speed headroom.

Availability

24FC128T-I/MS is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, and automotive body control modules requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for 24FC128T-I/MS 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 24FC128 belongs to Microchip's 24XX128 family of I²C EEPROMs engineered for low-voltage, high-reliability embedded data storage - specifically targeting applications demanding extended data retention, robust noise immunity, and seamless integration with resource-constrained MCUs.

FAQ

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

The 24FC128T-I/MS 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 rate is 400 kHz. This dual-speed capability allows the 24FC128T-I/MS to maintain high throughput in modern low-voltage systems while remaining compatible with legacy 3.3V/5V designs.

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

Yes, the 24FC128T-I/MS requires external pull-up resistors on both SDA and SCL 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 24FC128T-I/MS does not integrate internal pull-ups, so omission will result in bus failure.

How many devices can be connected on the same I²C bus using the 24FC128T-I/MS?

Up to two 24FC128T-I/MS devices can share one I²C bus due to its MSOP-8 package configuration, where pins A0 and A1 are not connected. Only A2 remains functional for chip addressing, yielding two possible slave addresses: 1010xxx0 (A2 = 0) and 1010xxx1 (A2 = 1). This differs from SOIC/TSSOP variants that support up to eight devices.

What happens if a page write crosses a 64-byte boundary on the 24FC128T-I/MS?

If a page write command attempts to cross a 64-byte physical page boundary, the 24FC128T-I/MS wraps the address back to the start of the current page instead of advancing to the next page. This causes unintended overwriting of earlier bytes in the same page. Application firmware must explicitly manage page boundaries - the 24FC128T-I/MS does not auto-segment writes across pages.

Is the 24FC128T-I/MS qualified for automotive applications?

The 24FC128T-I/MS is rated for industrial temperature (–40°C to +85°C) and is RoHS compliant, but it is not AEC-Q100 qualified. While it may function in some automotive cabin environments, Microchip designates the 24LC128 and certain 24AA128 variants for AEC-Q100 compliance. For under-hood or safety-critical use, the 24FC128T-I/MS should not be substituted without full requalification.