Microchip Technology 24AA04HT-I/ST

Overview

24AA04HT-I/ST from Microchip Technology Inc. is a 4-Kbit I²C-compatible serial EEPROM organized as two 256 × 8-bit blocks, operating from 1.7V to 5.5V with 400 kHz max clock frequency, 1 µA standby current, and hardware write-protect for the upper half-array (100h–1FFh). It is used in industrial sensor calibration storage and embedded system configuration retention.

For engineers reviewing the 24AA04HT-I/ST datasheet, 24AA04HT-I/ST pinout, 24AA04HT-I/ST application, or 24AA04HT-I/ST equivalent, key selection factors include its I²C interface compatibility, low-voltage operation down to 1.7V, page write buffer (16 bytes), half-array hardware write-protection, and industrial temperature range (–40°C to +85°C) in an 8-lead SOIC package.

Technical Context

The 24AA04HT-I/ST implements a two-wire I²C bus protocol with Schmitt-trigger inputs and slope-controlled outputs to suppress noise and eliminate ground bounce. Its internal address counter supports current-address, random, and sequential read modes, while ACK polling enables precise timing of write-cycle completion.

It uses a self-timed erase/write cycle with 5 ms maximum page write time and features a 16-byte page write buffer. The WP pin provides hardware-level protection for addresses 100h–1FFh when tied to VCC; A0–A2 pins are unconnected and may be left floating or tied to VSS/VCC without effect.

Key Specifications

Pinout & Package

24AA04HT-I/ST is packaged in an 8-lead SOIC (SN) with 3.90 mm body width and standard 1.27 mm pitch. Pin 1 is marked by a notch or dot; the package is RoHS-compliant and rated for industrial temperature operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24AA04HT-I/ST, the 24LC04BHT-I/ST offers identical packaging and interface but higher minimum supply voltage, while the AT24C04-PU omits hardware write-protection-making the 24AA04HT-I/ST optimal for 1.7V–5.5V systems requiring physical write-locking of critical memory regions.

Availability

24AA04HT-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration storage, embedded system configuration retention, and medical device safety parameter storage requiring stable component supply across extended production lifecycles.

Supply support for 24AA04HT-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 leading provider of microcontrollers, analog devices, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24AA04H family was designed specifically for space-constrained, low-power embedded systems needing reliable nonvolatile storage with I²C simplicity and industrial-grade environmental tolerance.

FAQ

What is the maximum clock frequency supported by the 24AA04HT-I/ST?

The 24AA04HT-I/ST supports up to 400 kHz when VCC is 2.5V or higher. At supply voltages between 1.7V and 2.5V, the maximum clock frequency is reduced to 100 kHz to maintain timing margin and signal integrity. This dual-speed capability allows seamless integration across mixed-voltage designs without external clock dividers or protocol translation.

How does the hardware write-protect feature work on the 24AA04HT-I/ST?

When the WP pin of the 24AA04HT-I/ST is tied to VCC, writes to memory addresses 100h–1FFh (upper 2 Kbit block) are disabled; reads remain fully functional. Tying WP to VSS enables full read/write access. This hardware-level lock prevents accidental or malicious firmware overwrites of critical calibration or safety data without requiring software intervention.

Can the 24AA04HT-I/ST operate reliably at 1.8V supply voltage?

Yes, the 24AA04HT-I/ST is fully specified for operation from 1.7V to 5.5V, including 1.8V nominal systems. At 1.8V, it maintains I²C compatibility at 100 kHz, delivers 1 µA standby current, and retains full functionality-including page writes, ACK polling, and hardware write-protection-making it ideal for modern ultra-low-power embedded platforms.

What is the purpose of the A0, A1, and A2 pins on the 24AA04HT-I/ST?

The A0, A1, and A2 pins on the 24AA04HT-I/ST are not internally connected and serve no functional role. They may be left floating or tied to VSS or VCC without affecting device operation. This simplifies PCB layout and eliminates address conflict concerns in multi-device I²C buses where other EEPROM families use these pins for device addressing.

Does the 24AA04HT-I/ST require external pull-up resistors on SDA and SCL lines?

Yes, the 24AA04HT-I/ST has open-drain SDA and SCL pins and requires external pull-up resistors. Typical values are 10 kΩ for 100 kHz operation and 2 kΩ for 400 kHz. Pull-up voltage must match the host controller's I/O voltage (e.g., 1.8V, 3.3V, or 5V) to ensure valid logic levels and meet rise-time specifications defined in the AC characteristics table.