Microchip Technology 24AA128-I/ST

Overview

24AA128-I/ST 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 1.7V to 5.5V, supports up to 400 kHz I²C clock frequency at industrial temperature (–40°C to +85°C), features hardware write-protection via the WP pin, and delivers 64-byte page write capability with ≤5 ms self-timed write cycle. It is used in firmware parameter storage for smart sensors and configuration retention in battery-powered IoT edge nodes.

For engineers reviewing the 24AA128-I/ST datasheet, 24AA128-I/ST pinout, 24AA128-I/ST application, or 24AA128-I/ST equivalent, key selection criteria include its 1.7V minimum supply voltage, industrial-grade temperature rating, SOIC-8 (ST) package compatibility, and support for cascaded multi-device I²C bus configurations up to eight units.

Technical Context

The 24AA128-I/ST 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 current-address, random, and sequential read modes. Its memory array is organized as 16,384 × 8 bits with 64-byte page boundaries.

Write protection is enforced by the WP pin sampled at the Stop bit of each write command; when tied to VCC, all array writes (0000h–3FFFh) are inhibited while reads remain fully functional. Addressing uses a 7-bit slave address (1010xxxR/W) where A2–A0 pins define device select bits, allowing up to eight devices on one bus (two for MSOP).

Key Specifications

Pinout & Package

24AA128-I/ST is supplied in an 8-lead SOIC package (JEDEC MS-012, body width 3.90 mm), marked "24AA128I" and "ST" per Microchip's marking convention. Pin 1 is top-left corner with notch or dot indicator.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC128-I/ST, the 24AA128-I/ST enables true single-supply operation down to 1.7V while maintaining identical packaging and I²C protocol compliance; versus AT24C128-10PU-2.7, it trades maximum clock speed for broader voltage range and automotive qualification - making it optimal for battery-constrained or safety-critical deployments.

Availability

24AA128-I/ST is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive body electronics requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for 24AA128-I/ST 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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory solutions, with global manufacturing and quality certifications including ISO 9001 and AEC-Q200.

The 24AA128 belongs to Microchip's 24XX128 family of I²C EEPROMs engineered for robust, low-power nonvolatile storage in harsh environments - targeting applications where data integrity, voltage flexibility, and long-term reliability are mandatory.

FAQ

What is the minimum operating voltage for the 24AA128-I/ST?

The 24AA128-I/ST operates down to 1.7V across its full industrial temperature range (–40°C to +85°C). This enables direct interface with 1.8V microcontrollers and energy-harvesting power supplies without level-shifting circuitry. The device maintains full I²C functionality, including 400 kHz clock support and reliable page writes, at this minimum voltage.

Does the 24AA128-I/ST support multi-device I²C bus configurations?

Yes, the 24AA128-I/ST supports cascading up to eight devices on a single I²C bus using hardware-configurable A2, A1, and A0 pins. Each device is assigned a unique 7-bit slave address (1010xxx) based on the logic levels applied to these pins. This allows expansion to 1 Mbit of contiguous address space when multiple 24AA128-I/ST units are deployed.

How does hardware write-protection work on the 24AA128-I/ST?

The WP pin on the 24AA128-I/ST provides hardware-level write inhibition: when tied to VCC, all write operations (byte and page) to the entire 128 Kbit array (addresses 0000h–3FFFh) are blocked, while read operations remain fully functional. The pin state is sampled at the Stop bit of each write command, ensuring protection cannot be overridden mid-cycle.

What is the maximum I²C clock frequency supported by the 24AA128-I/ST?

The 24AA128-I/ST supports up to 400 kHz I²C clock frequency when V_CC is 2.5V or higher. At V_CC < 2.5V, the maximum clock rate is 100 kHz. These limits are defined by AC timing parameters including THIGH (≥600 ns), TLOW (≥1300 ns), and TR/TF (≤300 ns), ensuring reliable communication across the specified voltage and temperature range.

Is the 24AA128-I/ST qualified for automotive applications?

Yes, the 24AA128-I/ST is AEC-Q100 qualified for automotive applications. It meets stress test requirements for temperature cycling, humidity bias, and ESD (≥4,000V HBM), and is rated for operation across the industrial temperature range (–40°C to +85°C), which aligns with AEC-Q100 Grade 3 specifications. This makes it suitable for body control modules and infotainment subsystems.