The CNY17F-4 is an optically-coupled isolator from Vishay. It features a built-in GaAlAs LED and a silicon avalanche photodiode in a single package. It provides a high degree of galvanic isolation (up to 4kV) between input and output for a variety of applications. When used as an opto-coupler, it is designed for low-level signal transmission between isolated circuits and offers low input current requirements, high speed switching, and good common mode transient immunity. The CNY17F-4 is widely used in power supplies, motor drives, factory automation systems, and telecommunications.