microsystems on silicon


Mains Voltage Zero-Cross Synchronized PIR Controller


The E931.98 is a mains voltage zero cross synchronized controller for passive infrared (PIR) applications that operates in conjunction with a conventional PIR detector. The signal from the detector is converted to a digital signal and evaluated for motion detection.

Detected motion is indicated with a push-pull output (REL) that is switched during mains voltage zero crossing. An algorithm adapts the switching point to the mains frequency and the delay of the specific relay used, ensuring the relay’s contacts will be closing on the voltage zero crossing point.

An input (OEN) enables or disables motion detection for day night sensing.

The LED output is activated when the PIR detector voltage is above the threshold that is defined by the sensitivity input (SENS) of the device.
It is possible to adjust the detection sensitivity and the output on-time (ONTIME) to suit most applications.

A built in shunt regulator (ENREG) enables the device to be used in a variety of applications with various supply voltages without the need for additional external components.

With the digital signal processing and one pulse motion sensing algorithm, the E931.98 is most suitable for mains powered outdoor motion sensor lights.

The integrated circuit is packaged in a cost effective SOIC-14 package.


  • Mains powered motion sensor lights that require relay switching on zero crossing.
  • PIR motion sensor lights.
  • Mains powered occupancy detectors.
  • Motion sensing applications with low cost relays, switching capacitive loads.


  • Adaptive zero cross mains voltage switching.
  • Digital signal processing.
  • On chip supply shunt regulator with enable.
  • Instantaneous settling after power up.
  • Low power consumption.
  • Excellent power supply rejection.
  • Insensitive to RF interference.
  • Motion detect output. (REL)
  • Inputs for sensitivity, on time and daylight sensor.