The UPC817XG-D04-T is an optocoupler, manufactured by Unisonic, with ROHS (Restriction of Hazardous Substances) certification. It is a DIP-4 package (Dual Inline Package) and has a phototransistor output. It is rated at 35V, 5000V, 50mA, 0.1V@1mA, 20mA, 1 6V, 1.2V DC.