How Opto-Isolators Prevent High Voltages from Affecting the System


An opto-isolator is an electronic component that connects two individual electrical circuits using a light sensitive optical interface. An opto-isolator, also known as an optocoupler or optical coupler, is a semiconductor device. It utilizes a short optical transmission path to shift electrical signals between circuits while making sure they remain electrically independent of each other.


An opto-isolator’s basic design comprises a light emitting diode (LED) that produces infra-red light combined with a semiconductor photo-sensitive device or a phototransistor which is used to detect the infra-red beam emitted from the LED. Both the photo-sensitive device and the LED are housed within a tightly packed body with metal clasps or legs that allow electrical connections.


These devices basically function by transferring electrical signals from one isolated circuit to another using light. These opto-isolators are known to prevent high voltages from affecting the system that is receiving these signals. Opto-isolators that are commercially available are capable of withstanding input-to-output voltages up to 10 kV. They are also capable of withstanding voltage transients that have speeds of up to 10 kV/μs.


Opto-isolators come in various combinations such as LED-LASCR (light-activated silicon-controlled rectifier), lamp-photoresistor pairs, and LED-photodiodes.