7 W offline converter with 800 V MOSFET — sizing the rail
The VIPER011LSTR is a monolithic offline switching regulator from ST that integrates a power MOSFET with an 800 V breakdown rating and a PWM controller in a single 10-SSOP package.
Fixed 60 kHz switching — transformer and filter sizing
The switching frequency is fixed at 60 kHz, which sets the transformer core cross-section and the corner frequency of the input EMI filter. At this frequency the internal MOSFET's switching losses are predictable, but the designer should confirm the transformer design does not push the core into saturation at the maximum duty cycle of 80%.
Protection set and supply range
On-chip fault protection covers current limiting, over-temperature, over-voltage, and short-circuit — no external sense resistor or comparator needed for basic protection.