Microchip Technology 24LC128T-I/MS

Overview

24LC128T-I/MS from Microchip Technology Inc. is a 128 Kbit (16K × 8) I²C-compatible serial EEPROM designed for nonvolatile data storage in low-power embedded systems. It operates from 2.5V to 5.5V, supports up to 400 kHz I²C clock frequency, features hardware write-protection via the WP pin, and delivers 1 µA max standby current at industrial temperature (–40°C to +85°C). It is commonly used in metering calibration storage, sensor configuration retention, and firmware parameter backup.

For engineers reviewing the 24LC128T-I/MS datasheet, 24LC128T-I/MS pinout, 24LC128T-I/MS application, or 24LC128T-I/MS equivalent, key selection criteria include its 2.5V minimum VCC, MSOP-8 package footprint, 64-byte page write buffer, and AEC-Q100-qualified variants for automotive subsystems requiring robust data integrity across thermal cycles.

Technical Context

The 24LC128T-I/MS implements a two-wire I²C interface with Schmitt-trigger inputs on SDA and SCL for noise immunity, and slope-controlled outputs to suppress ground bounce. Its internal address counter enables sequential reads across the full 128Kbit memory space, while cascading support for up to eight devices (or two in MSOP due to unconnected A0/A1 pins) allows scalable memory expansion.

Write operations are self-timed with a maximum 5 ms erase/write cycle; page writes accept up to 64 bytes before initiating the internal programming sequence. The device uses a dedicated hardware write-protect pin (WP), sampled at the STOP bit, to disable all write commands when pulled high - independent of software control or I²C address decoding.

Key Specifications

Pinout & Package

24LC128T-I/MS is housed in an 8-lead MSOP (Micro Small Outline Package) with 0.65 mm lead pitch and exposed pad option. Pin 1 is A0 (no-connect), Pin 2 is A1 (no-connect), Pins 3–8 are A2, VSS, SDA, SCL, WP, and VCC respectively - matching standard I²C slave pinout alignment for drop-in replacement in space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC128T-I/MS, the 24AA128T-I/MS extends voltage flexibility downward but sacrifices automotive qualification, while the AT24C128-MAHM-T offers alternate packaging but requires PCB redesign - making 24LC128T-I/MS optimal for space-constrained, thermally demanding industrial or automotive modules needing guaranteed 2.5V+ operation.

Availability

24LC128T-I/MS is available at Aetrix Electronics and suitable for smart metering, automotive body electronics, and industrial PLC I/O modules requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant manufacturing.

Supply support for 24LC128T-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 microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing infrastructure.

The 24LC128T-I/MS belongs to Microchip's 24XX128 family of I²C EEPROMs, engineered for reliable, low-power nonvolatile storage in automotive, industrial, and consumer applications where data integrity across wide temperature ranges is essential.

FAQ

What is the minimum supply voltage required for reliable operation of the 24LC128T-I/MS?

The 24LC128T-I/MS requires a minimum VCC of 2.5V for guaranteed operation across its full industrial temperature range (–40°C to +85°C). Below 2.5V, functionality is not specified - unlike the 24AA128 variant, which supports down to 1.7V. This 2.5V threshold ensures stable internal charge pump operation for EEPROM write cycles and robust I²C signal levels.

Does the 24LC128T-I/MS support AEC-Q100 qualification?

Yes, the 24LC128T-I/MS is AEC-Q100 qualified for automotive applications. The "I" suffix denotes Industrial temperature grade (–40°C to +85°C), and Microchip explicitly lists AEC-Q100 qualification in the device selection table and feature list of DS20001191T. This certification covers stress testing for temperature cycling, humidity, and ESD robustness required in automotive ECUs.

How many devices can be connected on a single I²C bus using the 24LC128T-I/MS?

Only two 24LC128T-I/MS devices can share one I²C bus. Because the MSOP package leaves A0 and A1 unconnected (NC), only A2 remains configurable for slave address selection - yielding just two possible addresses (1010001 and 1010011). This differs from SOIC or TSSOP variants, which support up to eight devices using all three address pins.

What is the function of the WP pin on the 24LC128T-I/MS, and when is it sampled?

The WP (Write-Protect) pin on the 24LC128T-I/MS disables all write operations - including byte and page writes - when pulled high to VCC. It is sampled at the STOP condition of each I²C write command, not continuously. Once sampled, the write-inhibit state persists for that command; toggling WP mid-cycle has no effect, ensuring deterministic protection during bus arbitration.

Can the 24LC128T-I/MS perform sequential reads across the entire 128 Kbit memory space?

Yes, the 24LC128T-I/MS supports full-sequence reads from address 0x0000 to 0x3FFF. Its internal address counter automatically increments after each byte transfer and rolls over from 0x3FFF to 0x0000 upon reaching the end. This enables uninterrupted streaming of configuration data or firmware metadata without host-side address management overhead.