Microchip Technology 24LC128T-I/SN

Overview

24LC128T-I/SN 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 clock frequency, features hardware write-protection via the WP pin, and delivers 1 million erase/write cycles with >200 years data retention. It is used in industrial sensor calibration, power meter configuration, and firmware parameter storage.

For engineers reviewing the 24LC128T-I/SN datasheet, 24LC128T-I/SN pinout, 24LC128T-I/SN application, or 24LC128T-I/SN equivalent, key selection criteria include its 2.5V minimum VCC, 8-lead SOIC (SN) package, I²C bus compatibility up to 400 kHz, page write buffer size of 64 bytes, and industrial temperature range (–40°C to +85°C).

Technical Context

The 24LC128T-I/SN implements a two-wire I²C interface with Schmitt-trigger inputs on SDA and SCL for noise immunity, slope-controlled outputs to suppress ground bounce, and internal address pointer logic enabling sequential reads across the full 128Kbit memory space. Its slave address uses fixed '1010' control code plus user-configurable A2/A1/A0 bits, supporting up to eight devices on one bus.

Write operations are self-timed and internally managed: byte writes complete in ≤5 ms, and page writes support up to 64 bytes per command with automatic wrap-around handling. The device samples the WP pin at the Stop bit to enable or disable writes, and supports acknowledge polling to detect write completion without fixed timing delays.

Key Specifications

Pinout & Package

24LC128T-I/SN is housed in an 8-lead plastic small outline (SOIC) package, narrow body (3.90 mm), JEDEC MS-012AC compliant, with gull-wing leads and matte tin (Sn) finish. Pin 1 is marked by a beveled corner or notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC128T-I/SN, the 24AA128T-I/SN extends low-voltage operation but lacks extended temperature support, while the AT24C128N-10SU-2.7 offers comparable performance at lower cost but without automotive qualification - making 24LC128T-I/SN the preferred choice for industrial-grade reliability with defined 2.5V minimum supply.

Availability

24LC128T-I/SN is available at Aetrix Electronics and suitable for industrial sensor calibration, smart meter configuration, and automotive body control module designs requiring stable component supply across multi-year production cycles.

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

The 24LC128T-I/SN belongs to Microchip's 24XX128 family of I²C serial EEPROMs, engineered for reliable, low-power nonvolatile storage in industrial, automotive, and consumer applications demanding long data retention and high endurance.

FAQ

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

The 24LC128T-I/SN requires a minimum VCC of 2.5V for guaranteed operation across its full industrial temperature range (–40°C to +85°C). Operation below 2.5V is not specified and may result in unpredictable write failures or communication errors. This distinguishes it from the 24AA128 variant, which supports down to 1.7V.

How does the WP pin function on the 24LC128T-I/SN during a write cycle?

The WP pin on the 24LC128T-I/SN is sampled only at the Stop condition edge of each write command. When tied to VCC, it inhibits all write operations (byte and page) while permitting reads; when tied to VSS, writes are enabled. Toggling WP during an active write cycle has no effect - the decision is latched once per command.

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

Yes, the 24LC128T-I/SN supports sequential reads across the full 128Kbit address space (0x0000 to 0x3FFF). Its internal address pointer auto-increments after each byte transfer and rolls over from 0x3FFF to 0x0000 upon acknowledgment, enabling uninterrupted streaming of stored data without host-side address management.

What is the maximum number of 24LC128T-I/SN devices that can be connected to a single I²C bus?

Up to eight 24LC128T-I/SN devices can be connected to one I²C bus using unique combinations of the A2, A1, and A0 pins. Each device responds only to its assigned 3-bit chip address, allowing shared bus access without address conflicts - provided pull-up resistors are sized appropriately for total bus capacitance.

Does the 24LC128T-I/SN support 1 MHz I²C operation?

No, the 24LC128T-I/SN is rated for a maximum clock frequency of 400 kHz. Only the 24FC128 variant in the same family supports 1 MHz operation. Attempting 1 MHz communication with the 24LC128T-I/SN will result in timing violations, failed ACKs, and unreliable data transfer.