AP3928 Universal AC Step Down Power Switcher Diodes Incorporated AP3928 Universal AC Step Down Power Switcher is intended for home appliances and IoT applications with a non-isolated buck solution. The AP3928 integrates a 700V high-performance MOSFET and coordinates with a single-winding inductor. This high-level integration results in fewer external components and allows a low bill of materials (BOM) cost solution.