STMicroelectronics LSM303AHTR

Overview

LSM303AHTR from STMicroelectronics is an ultra-compact eCompass system-in-package integrating a 3-axis accelerometer and 3-axis magnetometer. It delivers ±2/±4/±8/±16 g selectable acceleration full scales, ±50 gauss magnetic dynamic range, 16-bit data output, and operates from 1.71 V to 1.98 V analog supply. Used in tilt-compensated compasses and motion-activated functions for handheld and wearable devices.

For engineers reviewing the LSM303AHTR datasheet, LSM303AHTR pinout, LSM303AHTR application, or LSM303AHTR equivalent, key selection considerations include dual-sensor synchronization, embedded step detection, FIFO buffering for accelerometer-only data, I²C/SPI interface flexibility (up to 3.4 MHz), and operation across –40 °C to +85 °C.

Technical Context

The LSM303AHTR implements independent power control for its accelerometer and magnetometer blocks, enabling selective activation to minimize system-level current draw. Accelerometer output data rates span 1 Hz to 6400 Hz; magnetometer ODR ranges from 10 Hz to 100 Hz - with no shared timing domain between sensors.

It integrates dedicated digital functions including step detector, step counter, significant motion recognition, and 6D/4D orientation detection - all executed internally without host processor intervention. The 256-level FIFO applies exclusively to accelerometer data and supports bypass, continuous, and FIFO modes with configurable thresholds.

Key Specifications

Pinout & Package

LSM303AHTR is housed in a 2.0 mm × 2.0 mm × 0.7 mm LGA-12 package with exposed thermal pad. Pin assignment follows STMicroelectronics' standardized land grid array layout for compact PCB footprint and reliable reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BNO055 and LSM9DS1, the LSM303AHTR offers lowest power and smallest footprint for pure eCompass and step-counting use cases - trading off fused output and gyro capability for extended battery life and simplified BOM.

Availability

LSM303AHTR is available at Aetrix Electronics and suitable for tilt-compensated compasses, pedometers, and display orientation control requiring stable component supply in high-volume consumer electronics production.

Supply support for LSM303AHTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in MEMS sensors, microcontrollers, and power management ICs for industrial, automotive, and consumer markets.

The LSM303AHTR belongs to ST's ultra-low-power eCompass product line, designed specifically for battery-constrained portable devices requiring high-accuracy heading and motion awareness without host computational burden.

FAQ

What communication interfaces does the LSM303AHTR support?

The LSM303AHTR supports both I²C and SPI serial interfaces. I²C operates at standard (100 kHz), fast (400 kHz), fast-plus (1 MHz), and high-speed (3.4 MHz) modes. SPI uses 4-wire configuration with CS, SCLK, SDI, and SDO pins, and supports up to 10 MHz clock rates per ST's electrical characteristics table.

Does the LSM303AHTR include hardware-based step counting?

Yes - the LSM303AHTR embeds a dedicated step detection and counting engine that runs autonomously within the device. It generates interrupts on detected steps and maintains a 16-bit step count register accessible via I²C or SPI, eliminating the need for host-side motion algorithm implementation.

Can the accelerometer and magnetometer operate simultaneously at different output data rates?

Yes - the LSM303AHTR allows independent configuration of accelerometer ODR (1 Hz to 6400 Hz) and magnetometer ODR (10 Hz to 100 Hz). They share no timing dependency, enabling optimized power/performance trade-offs - for example, high-rate accel sampling for impact detection while magnetometer runs at 10 Hz for compass stability.

Is the 256-level FIFO available for both sensors?

No - the 256-level FIFO is allocated exclusively to the accelerometer data path. Magnetometer data must be read in real time or buffered externally. This architecture reflects the typical usage pattern where high-frequency motion data benefits most from burst-read efficiency, while magnetic field updates are lower priority and less time-critical.