Datasheet

Theory of Operation

Pyroelectric devices, such as the PIR sensor, have elements made of a crystalline material that generates

an electric charge when exposed to infrared energy. The changes in the amount of infrared energy

striking the element change the voltages generated, which are measured by an on-board amplifier. The

device contains a Fresnel lens, which focuses the infrared signals onto the element. As the ambient

infrared signals change rapidly, the on-board amplifier trips the output to indicate motion.

The onboard jumper allows the user to select between normal operation and reduced sensitivity. The

sensitivity of the PIR Sensor varies with temperature and other environmental conditions. Generally,

when in reduced sensitivity mode, the PIR sensor will detect an object at up to half the distance it would

in normal operating mode. For more information, see the Range section below.

Range

The PIR Sensor’s range is affected by:

 The sensitivity jumper setting

 The size and thermal properties of nearby objects

 Environmental conditions including ambient temperature and light sources

The graph below depicts the approximate effects of known ambient temperatures on the PIR Sensor’s

detection range of an average adult.

The graph below depicts the approximate effects of known temperatures on the PIR Sensor’s detection

range of an adult.

Note: This device is designed for indoor use. Operation outside or in extreme

temperatures may negatively affect stability. Direct exposure to sunlight or other forms of radiant heating

may cause undesired operation.