The OPI110 consists of an infrared Light Emitting Diode (LED) and a NPN silicon phototransistor. The devices are sealed in a pre-cast opaque housing with a optically transmissive path between the LED and the phototransistor. This series is designed for transmission of information between one power supply voltage and another where the potentials during surge conditions are not greater than the 10KV isolation voltage. The OPI110 is used in applications where high voltage isolation between input and output no greater than 10,000 volts is required. It also offers electrical isolation in dirty environments. Medical, industrial, and office equipment are also common.