STMicroelectronics, a global semiconductor supplier serving customers across the spectrum of electronics applications, is launching a new human presence and motion detector to enhance security systems, home automation equipment and IoT devices that typically use passive infrared (PIR) detection. .
The STHS34PF80 sensor contains thermal transistors that can detect stationary objects, unlike conventional PIR detectors that require the detected object to be moving to produce a measurable sensor response. Additionally, while PIRs require Fresnel lenses to detect moving objects, ST's new detector allows for simpler, lensless construction.
“Today’s smart homes, smart buildings and IoT applications need accurate presence sensing to improve control of systems such as lighting, heating, security and security monitoring for a sustainable future,” said Simone Ferri, GM, AMS MEMS Sub-Group, STMicroelectronics. “Our new STHS34PF80 is a cost-effective, ultra-low power sensor that allows building automation to operate consistently regardless of whether detected occupants are moving or not. It is made using an innovative combination of CMOS chip manufacturing, silicon micromachining and low voltage circuit design capabilities.”
Incorporating a smart algorithm for presence and motion detection, the STHS34PF80 targets alarms and security systems, home automation, smart lighting, IoT devices, smart cabinets and smart wall panels. Its four-meter lensless range and 80° field of view cover a large area in front of the sensor.
With an operating current of 10 µA, power consumption is lower than a conventional PIR, and the 3.2 x 4.2 x 1.455 mm surface mount package is compact and suitable for high-speed automated assembly. The sensor has high resistance to unwanted effects of direct lighting and high immunity to electromagnetic interference (EMI).
The STEVAL-MKI231KA simplifies experimentation with the STHS34PF80. Connecting to the X-NUCLEO-IKS01A3 or STEVAL-MKI109V3 allows developers to use ST's Unico-GUI graphical interface to configure the IR sensor and take measurements within a simplified workflow. Drivers for STHS34PF80 are available on GitHub.
Additionally, a ready-to-use library for compensation and presence detection of people or objects is available in X-CUBE-MEMS1 software package. Users can quickly start running simple applications by leveraging the STHS34PF80 and testing the results to begin creating an application.
Technical overview
The STHS34PF80 contains thermal MOSFETs (TMOS) that are sensitive to the heating effects of infrared radiation incident on their gates, as well as digital readout circuits efficiently integrated on the same chip using ST's mature and reliable silicon-on-insulator (SOI) CMOS technology. . . The SOI architecture facilitates micromachining with ST's proven MEMS (microelectromechanical systems) processes to thermally isolate the TMOS for accurate temperature sensing.
The TMOS is supplied with a subthreshold voltage, below that required to fully turn on the transistor. In this mode, the drain source current is highly temperature dependent and produces an accurately measurable response to minimal infrared radiation. This allows the sensor to detect human presence, through infrared emissions, whether the person is moving or stationary.
Another benefit of subthreshold operation is that the transistor consumes very low power, allowing the battery-powered sensors containing the STHS34PF80 to operate for long periods between charging or battery replacement.
Furthermore, standard CMOS manufacturing technology ensures cost-effective production of sensors with high wafer yield while also taking advantage of sub-micron transistor geometry for small-dimension sensors. This is in contrast to PIR sensors, whose sensitivity may depend on the size of the pyroelectric pixel. Additionally, the integrated digital interface allows direct connection to the host without analog front-end circuitry.
