March 28, 2026 – Austin, TX – Silicon Labs Streamlines Wireless PIR Design
Silicon Labs has announced the SiWx917-PIR, a new system-on-chip (SoC) that integrates a Wi-Fi 6 radio, Bluetooth LE, and a dedicated analog front-end for PIR sensors into a single package. The device is designed to simplify the development of wireless motion sensors, reducing component count and PCB area by up to 70% compared to discrete designs.
The SiWx917-PIR is available now for sampling, with volume production expected in Q4 2026.
Technical Specifications
- Processor: ARM Cortex-M33 (200 MHz) with TrustZone security
- Radio: Wi-Fi 6 (802.11ax) + Bluetooth LE 5.4
- PIR analog front-end: Dual-channel programmable gain amplifier (40-80 dB)
- ADC: 16-bit sigma-delta with 1 µV resolution
- On-chip DSP: Motion detection, classification, and timing
- Power consumption: 5 µA in sleep (PIR monitoring), 50 µA in Wi-Fi standby
- Package: 6mm × 6mm QFN (56-pin)
- Price: $2.99 (10,000-unit quantities)
Key Innovations
Integrated PIR Analog Front-End
The SiWx917-PIR includes a complete analog signal chain for PIR sensors:
- Dual-channel programmable gain amplifier (40-80 dB gain)
- Programmable high-pass and low-pass filters (0.1 Hz to 100 Hz)
- 16-bit ADC with differential inputs
- Automatic offset cancellation
- Built-in voltage reference and bias generation
This integration eliminates the need for external op-amps, comparators, and passive components, reducing BOM cost and simplifying PCB layout.
On-Chip Motion Processing
The SoC includes dedicated hardware for motion detection:
- Programmable threshold detection with hysteresis
- Direction detection for dual-element sensors
- Configurable hold time (0.1s to 30 minutes)
- Block time configuration (0s to 10 seconds)
- Wake-on-motion interrupt for ultra-low power operation
Machine Learning Accelerator
The SiWx917-PIR includes a dedicated neural network accelerator (20 GOPS) that can run classification models locally. Silicon Labs provides pre-trained models for:
- Human vs. pet discrimination
- Vehicle detection
- Environmental noise rejection
- Activity classification (walking, running, sitting)
Wi-Fi 6 Connectivity
The integrated Wi-Fi 6 radio supports:
- 2.4 GHz and 5 GHz bands
- OFDMA for efficient multi-device communication
- Target Wake Time (TWT) for extended battery life
- WPA3 security
Power Management
The SiWx917-PIR is optimized for battery-powered operation:
- Sleep mode (PIR only): 5 µA
- Wi-Fi standby (TWT): 50 µA
- Wi-Fi active (100 ms transmit): 150 mA peak
- PIR inference (neural network): 15 mA for 20 ms
- Supply voltage: 1.8V to 3.6V
With typical usage (50 motion events/day, 1 Wi-Fi transmission per event), average current is approximately 10 µA, enabling 5+ year battery life from a CR2032 coin cell.
Development Tools
Silicon Labs offers a comprehensive development ecosystem:
- SiWx917-PIR-EVB: Evaluation board with pre-mounted PIR sensor and lens ($79)
- Simplicity Studio: IDE with PIR examples and configuration tools
- Mobile App: iOS/Android app for configuration and testing
- Cloud Integration: Reference code for AWS IoT, Azure IoT, and Google Cloud
Target Applications
- Wireless security sensors (direct to cloud via Wi-Fi)
- Smart home motion detectors
- Building automation occupancy sensors
- IoT-enabled lighting controls
- Elderly care monitoring systems
Industry Reaction
“The SiWx917-PIR represents a significant step forward in sensor integration,” said a smart home industry analyst. “By combining the PIR analog front-end, processing, and Wi-Fi connectivity on a single chip, Silicon Labs has made it dramatically easier to create battery-powered motion sensors that connect directly to the cloud. This will accelerate the proliferation of wireless motion sensing.”
Conclusion
Silicon Labs’ SiWx917-PIR demonstrates the trend toward increased integration in sensor design. By combining PIR signal conditioning, processing, and wireless connectivity in a single package, the SoC enables new classes of battery-powered, cloud-connected motion sensors.