An optocoupler IC, also known as an opto-isolator or photocoupler, is a semiconductor device which is used to couple isolated circuits. Within an optocoupler you will find a light emitter and a light sensor. Optocouplers usually come in a semiconductor package, such as SOIC or PDIP.How does an optocoupler IC work?Optocouplers work by transferring energy from one circuit to another circuit via an optical transmission path, while providing electrical isolationThe light emitter device can come in the form of an LED (light emitting diode) that produces IR or visible light, or a laser diode. The light emitter receives the input and converts it into a light signal. The light detector senses the light emitter and converts it back into an electrical signal.Optocouplers are often used in high-voltage applications to block the high voltages and variations in voltage. This ensures that, if there is a spike in one part of a circuit, it will not affect other parts. Therefore they are ideal for applications which may experience variations in voltage.Types of Optocoupler:• Resistive• Photodiode• Phototransistor• BidirectionalOutput Types• CMOS• Darlington• IGBT Gate Drive• Logic Gate• MOSFET• Photodarlington• Phototransistor• Single Transistor• TRIAC