microsystems on silicon


Low Power Controller for PIR Applications


The E931.97 operates in conjunction with a conventional PIR detector. The signal from the detector is converted to a digital signal and evaluated for motion detection.

Motion is indicated with a push-pull output (REL). A Schmitt trigger input (OEN) is provided which allows the user to active or deactivate motion detection. A light dependent resistor (LDR) can be directly connected to disable switching during darkness or daylight.

The LED output is activated whenever the output voltage of the PIR detector is above the threshold, which is defined by the DC voltage on the SENS input.

The inputs for sensitivity (SENS) and on-time (OT) allow the user to choose from a wide range of settings.

The integrated shunt voltage regulator can be activated by the user through the ENVREG input. The E931.97 can be operated directly from batteries or regulated supply voltages ranging from 2.7 to 3.6V. In this case, the voltage regulator needs to be switched off and the user can benefit from the very low current consumption.

In applications with higher voltages, the user would activate the on chip shunt regulator, which generates a stable supply voltage of 3V for the E931.97 and the PIR detector.

E931.97 integrated circuit is packaged in a cost effective SOIC-14 and TSSOP-14 packages.


  • PIR motion sensors for security
  • PIR motion sensor lights
  • Occupancy detectors
  • Battery powered and wireless motion sensors
  • Toys


  • Digital signal processing
  • On chip supply shunt regulator with enable
  • Low power consumption
  • Instantaneous settling after power up
  • Signal above threshold indication (LED)
  • Motion detect output (REL)
  • Inputs for sensitivity, on time and daylight sensor