Microchip Technology 24LC128-E/SN

Overview

24LC128-E/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 µA standby current at industrial-extended temperature (–40°C to +125°C). It is commonly used in metering calibration storage, sensor configuration retention, and firmware parameter backup.

For engineers reviewing the 24LC128-E/SN datasheet, 24LC128-E/SN pinout, 24LC128-E/SN application, or 24LC128-E/SN equivalent, key selection considerations include its 8-lead SOIC (SN) package, extended-temperature qualification, 64-byte page write buffer, and compatibility with standard I²C masters across automotive, industrial, and IoT edge devices.

Technical Context

The 24LC128-E/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 cascading support for up to eight devices on a single bus using A0–A2 address pins. Its internal architecture includes a 64-byte page latch, self-timed erase/write cycle, and an address pointer that auto-increments during sequential reads.

It uses a CMOS EEPROM array with >1 million endurance cycles and >200 years of data retention. 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

24LC128-E/SN is housed in an 8-lead narrow SOIC package (Microchip drawing C04-057-SN), measuring 3.90 mm body width, with gull-wing leads and JEDEC-standard footprint. Pin 1 is marked by a beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA128-I/SN and 24FC128-I/SN, the 24LC128-E/SN uniquely combines extended-temperature operation (–40°C to +125°C) with 400 kHz I²C performance and 2.5–5.5V supply compatibility - making it the only option qualified for under-hood automotive and high-reliability industrial deployments requiring both thermal robustness and deterministic timing.

Availability

24LC128-E/SN is available at Aetrix Electronics and suitable for smart metering, automotive sensor calibration, and industrial PLC configuration requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 24LC128-E/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, FPGA, and memory solutions, serving automotive, industrial, communications, and consumer markets with vertically integrated silicon and development tools.

The 24LC128-E/SN belongs to Microchip's 24XX128 family of I²C EEPROMs, engineered specifically for reliable, low-power nonvolatile storage in harsh environments - emphasizing endurance, data retention, and AEC-Q100 compliance for mission-critical applications.

FAQ

What is the maximum I²C clock frequency supported by the 24LC128-E/SN?

The 24LC128-E/SN supports up to 400 kHz I²C clock frequency across its full V_CC range of 2.5V to 5.5V. Unlike the 24FC128 variant, it does not support 1 MHz operation. This 400 kHz limit ensures robust noise immunity and timing margin in electrically noisy industrial and automotive applications where the 24LC128-E/SN is typically deployed.

Does the 24LC128-E/SN require external pull-up resistors on SDA and SCL lines?

Yes, the 24LC128-E/SN requires external pull-up resistors on both SDA and SCL lines because these pins are open-drain. Recommended values are 2 kΩ for 400 kHz operation and 10 kΩ for 100 kHz. The exact value depends on bus capacitance and desired rise time; insufficient pull-up strength can cause I²C communication failures or timeout errors in the 24LC128-E/SN.

How does hardware write-protection work on the 24LC128-E/SN?

Hardware write-protection on the 24LC128-E/SN is controlled by the WP pin: when tied to VCC, all write operations (byte and page) are inhibited while read access remains fully functional. The WP state is sampled only at the Stop condition of each write command, so toggling WP mid-transaction has no effect. This provides deterministic, non-software-dependent memory lockout - a key safety feature in the 24LC128-E/SN.

Can multiple 24LC128-E/SN devices share the same I²C bus?

Yes, up to eight 24LC128-E/SN devices can share a single I²C bus using the A0, A1, and A2 address pins to configure unique 3-bit chip addresses. Each device must have a distinct combination of logic levels on these pins (tied to VSS or VCC). This allows scalable memory expansion up to 1 Mbit total capacity without additional I²C controllers - a core capability of the 24LC128-E/SN.

What is the page write buffer size of the 24LC128-E/SN, and why does it matter?

The 24LC128-E/SN features a 64-byte page write buffer, meaning up to 64 bytes can be loaded into the internal latch and written to memory in a single I²C transaction after the Stop condition. This reduces bus overhead significantly versus individual byte writes - for example, writing 64 bytes takes one transaction instead of 64 - improving system efficiency and minimizing bus contention in multi-master designs using the 24LC128-E/SN.