20 W flyback converter with 800 V avalanche-rugged MOSFET
The STMicroelectronics VIPER37LD is an offline flyback converter from the VIPer™ plus series, integrating an 800 V avalanche-rugged power MOSFET and PWM controller in a 16-SOIC package. It delivers up to 20 W in an isolated flyback topology, switching at 60 kHz. The 800 V breakdown voltage allows direct connection to rectified mains up to 265 VAC with margin for line surges, while the 60 kHz switching frequency keeps the transformer size manageable without excessive core losses.
Built-in fault protection includes current limiting, over-temperature shutdown, and over-voltage protection — covering the common failure modes in an offline supply without external supervisory ICs. The 14 V startup voltage and 8.5 V to 23.5 V supply range match standard auxiliary winding designs.
For new designs, this removes the obsolescence risk that haunts older offline converter parts.