Microchip Technology 24LC128T-I/SM

Overview

24LC128T-I/SM from Microchip Technology is a 128 Kbit (16K × 8) I²C-compatible serial EEPROM with hardware write-protection, 64-byte page write buffer, and industrial temperature range (–40°C to +85°C). It operates from 2.5V to 5.5V, supports up to 400 kHz clock frequency, and delivers ≤3 mA write current and ≤1 µA standby current. It is used in embedded systems for parameter storage, calibration data retention, and firmware configuration in programmable logic controllers.

For engineers reviewing the 24LC128T-I/SM datasheet, 24LC128T-I/SM pinout, 24LC128T-I/SM application, or 24LC128T-I/SM equivalent, key selection criteria include VCC min/max compliance (2.5–5.5V), I²C timing at 400 kHz, WP pin behavior, 64-byte page boundary handling, and SOIC-8 package mechanical fit.

Technical Context

The 24LC128T-I/SM implements a two-wire I²C slave interface with Schmitt-trigger inputs on SDA/SCL for noise immunity and slope-controlled outputs to suppress ground bounce. Its internal address pointer supports sequential, random, and current-address read modes across the full 128Kbit memory space.

Write operations are self-timed and internally managed: byte writes complete in ≤5 ms, and page writes (up to 64 bytes within a single physical page) also require ≤5 ms. The device uses an on-chip high-voltage generator for EEPROM programming and includes hardware write-protection via the WP pin, which disables all write cycles when pulled high.

Key Specifications

Pinout & Package

24LC128T-I/SM is supplied in an 8-lead SOIC (SN) package per Microchip drawing C04-057-SN, 3.90 mm body width, with gull-wing leads and standard JEDEC SOIC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA128T-I/SM, the 24LC128T-I/SM guarantees stable 400 kHz operation across its full 2.5–5.5V range and includes dedicated hardware write-protection - making it more suitable for industrial control and automotive applications where voltage margins and data integrity are critical. Against AT24C128-10PU-2.7, it trades maximum speed for enhanced reliability features including WP and stricter AC timing.

Availability

24LC128T-I/SM is available at Aetrix Electronics and suitable for industrial PLCs, medical instrumentation, automotive body control modules, and smart energy meters requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 24LC128T-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 microcontrollers, analog components, and memory solutions, serving industrial, automotive, and consumer markets with high-reliability silicon and development tools.

The 24LC128T-I/SM belongs to Microchip's 24XX128 family of I²C serial EEPROMs, designed specifically for robust, low-power nonvolatile data storage in embedded systems where write endurance, data retention, and interface simplicity are essential.

FAQ

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

The 24LC128T-I/SM requires a minimum VCC of 2.5V for guaranteed operation across its full industrial temperature range (–40°C to +85°C). Unlike the 24AA128 variant, it is not rated for operation below 2.5V - attempting to power the 24LC128T-I/SM at 1.8V or 2.2V may result in undefined behavior, failed writes, or loss of I²C acknowledgment. Always verify VCC stability during brown-out conditions in your target application.

Does the 24LC128T-I/SM support 1 MHz I²C clock frequency?

No, the 24LC128T-I/SM does not support 1 MHz I²C operation. Its maximum clock frequency is 400 kHz across its entire specified VCC range (2.5V–5.5V). Only the 24FC128 variant in the same family supports 1 MHz - the 24LC128T-I/SM's AC characteristics, including THIGH, TLOW, and TR/TF, are validated only up to 400 kHz. Using higher frequencies risks timing violations and communication failures.

How does the WP pin function on the 24LC128T-I/SM during active write cycles?

The WP pin on the 24LC128T-I/SM is sampled at the Stop condition of each write command. If WP is high at that instant, the write cycle is inhibited - the device acknowledges the command but performs no memory update. Toggling WP during an ongoing internal write has no effect; the cycle completes or aborts based solely on WP state at the Stop bit. This ensures deterministic, glitch-immune write protection.

Can the 24LC128T-I/SM perform sequential reads across the full 128Kbit address space?

Yes, the 24LC128T-I/SM supports seamless sequential reads across the entire 128Kbit (0000h–3FFFh) address space. After reading address 3FFFh, the internal address pointer automatically rolls over to 0000h upon receipt of the next Acknowledge. This enables continuous streaming of stored configuration or log data without software address management - provided the master continues issuing Acknowledge signals until the final byte.

What is the physical page size of the 24LC128T-I/SM, and why does it matter for page writes?

The 24LC128T-I/SM has a physical page size of 64 bytes (addresses 0000h–003Fh, 0040h–007Fh, etc.). Page writes are restricted to a single physical page - attempting to write across a boundary (e.g., starting at 003Eh with 5 bytes) causes wraparound to the start of the same page, overwriting prior data. This constraint requires firmware to align page writes and split multi-page transfers, directly impacting buffer management and write efficiency.