BMI423 Inertial Measurement Unit

Introduction

Bosch’s BMI423 is a low-power inertial measurement unit (IMU) that combines a 24-bit digital accelerometer and 24-bit digital gyroscope in a compact LGA package. The device is notable for combining configurable motion sensing with integrated, on-sensor functions such as voice activity detection, gesture recognition, step detection, and tap detection.

With selectable measurement ranges, output data rates up to 6.4 kHz, and I3C, I²C, or SPI host connectivity, the BMI423 is intended for embedded designs that need local motion data acquisition and event detection without relying exclusively on continuous host-side processing.

What it does

The BMI423 measures linear acceleration and angular rate. Its accelerometer supports selectable ranges from ±2 g through ±32 g, while the gyroscope offers ranges from ±125°/s to ±4000°/s. Both sensing paths provide 24-bit digital resolution.

Selectable output data rates span 12.5 Hz to 6.4 kHz, allowing a design to trade sampling rate against system requirements. A 4 KB on-chip FIFO can buffer sensor data, helping a host processor retrieve samples in batches rather than servicing every measurement individually.

Alongside raw inertial data, the IMU includes motion-oriented functions for voice activity, gestures, steps, and taps. Two interrupt pins are provided for connecting sensor events to the host system.

The device operates from a 1.62 V to 3.63 V VDD supply, with a separate VDDIO range of 1.08 V to 3.63 V. Specified current consumption includes 25 µA in acceleration operation, 615 µA in high-performance mode, 322 µA in low-power mode, and 13.5 µA in suspend mode.

Applications

• Wearable devices requiring step, gesture, or tap detection
• Battery-powered motion-tracking nodes
• Compact input devices using motion-based user interaction
• Embedded systems that need accelerometer and gyroscope measurements through I3C, I²C, or SPI
• Motion-event sensing designs that can use FIFO buffering and interrupt-driven host operation

Design considerations

The BMI423 is supplied in a 2.5 mm × 3 mm × 0.8 mm LGA package, making board layout, assembly capability, and available placement area important considerations for compact designs.

Designers can select among I3C, I²C, and SPI interfaces according to host-controller capability and bus architecture. The separate VDD and VDDIO supply ranges should also be considered when interfacing the sensor with low-voltage logic. For data handling, the 4 KB FIFO and two interrupt pins support buffered and event-driven integration approaches.

The operating temperature range is specified from -40°C to +85°C. Measurement-range selection, output data rate, operating mode, and current consumption should be chosen to suit the required motion profile and power budget.

Availability and further information

The source/distributor and datasheet links on this page provide further information on the Bosch BMI423 IMU, including device documentation and sourcing details.