AU1Fx Surface-Mount Ultrafast Avalanche Rectifiers Vishay AU1Fx Surface-Mount Ultrafast Avalanche Rectifiers are ideal for general purpose rectification of power supplies, inverters, converters, and freewheeling diodes. This includes the consumer, automotive, and telecommunication industries. They feature a low profile package, making them ideal for automotive placement. The rectifiers have ultrafast recovery times and a low reverse current.