STEVAL-ISA012V1: 3.3V @ 100mA, 5V @ 10mA, 90 ~ 450V

This reference design represents a cost effective solution for low power high voltage power supplies. It has been developed to cover applications requiring an ultra-wide input voltage range (between 90 and 450 VAC), typical of 3-phase applications. This requires the use of very high voltage components, which increases cost, size, weight and the overall complexity of the power supply.

The circuit includes a switching transistor connected between the input rectifier and the DC bulk capacitor (STMicroelectronics patent). The series switch limits the DC input voltage of the power converter by means of a driving circuit; thus the SMPS primary transistor can be selected as a standard part as well as a smart power primary IC.