Photocoupler Application Notes 1 Rev. 1.0 2019-04-25 ©2019 Toshiba Electronic Devices & Storage Corporation Outline: Photovoltaic-output photocouplers(photovoltaic couplers), which incorporate a photodiode array as an output device, are commonly used in combination with a discrete MOSFET(s) to form a semiconductor relay. This application note discusses the electrical characteristics and application circuits of photovoltaic-output photocouplers. Basic Electrical Characteristics and Application Circuit Design of Photovoltaic Couplers for MOSFET Drive for Relays