This is a type of optocoupler, which is a device that uses light to transfer electrical signals between two isolated circuits. It has an input transistor, a light-emitting diode, and a photosensitive transistor. It is typically used as a digital isolator, a high-voltage detector, and for switching applications requiring high-isolation. The OSM5DK56A1A has an isolation voltage of 5,500 VRMS min, a switching current of 5 mA, and a response time of 7.5 microseconds.