• PREMA Semiconductor GmbH

Optical Encoder

An arrangement of 3 or more PR5101 can be used as an optical encoder. IC1 sets the reference voltage for the comparators in IC2 and IC3. If a chopper wheel rotates over IC2 and IC3, the movement of the wheel is indicated by the LEDs connected to OUT_CMP of IC2 and IC3, respectively. These two signals can be used to determine the speed and the direction of the rotation. The comparator level for IC2 and IC3 can be adapted automatically to the intensity of the light source by a reference level from IC1. Therefore, if the brightness of the light source decreases, e.g. by soiling or aging, its influence is compensated.