800 V breakdown, 12 W output — the off-line workhorse
The STMicroelectronics VIPER0PHD is a monolithic off-line switching regulator from the VIPer™ plus family, integrating a power MOSFET with an 800 V breakdown voltage and a PWM controller in a single 16-SOIC package. It delivers up to 12 W across buck, buck-boost, and flyback topologies, making it a fit for auxiliary power supplies, appliance control boards, and industrial bias rails where a compact, single-chip solution is preferred over a discrete controller-plus-MOSFET pair.
Switching frequency and topology flexibility
The fixed 120 kHz switching frequency is a known value for transformer design and EMI filter sizing — no external timing resistor or capacitor needed. The part supports output isolation as either isolated or non-isolated, so the same BOM line can serve a flyback converter with an optocoupler feedback loop or a simple buck regulator for a non-isolated bias rail. Duty cycle maxes out at 80%, which is typical for a current-mode controller and sets the minimum input voltage at which the output stays regulated. The 4.5 V to 30 V Vcc supply range lets the IC be powered from an auxiliary winding or a regulated bias rail without an extra linear regulator.
On-chip fault protection covers current limiting, over-load, over-temperature, and short-circuit — four protection mechanisms that reduce external sense-resistor count and simplify the protection loop.