The STMicroelectronics VIPER27LDTR is a monolithic offline flyback switching regulator from the VIPer™ plus series. It integrates the 800 V avalanche-rugged power MOSFET and the PWM controller in a single 16-SOIC surface-mount package, simplifying the design of isolated AC-DC converter stages.
The 800 V breakdown voltage on the integrated MOSFET gives you headroom for universal AC input (85–265 VAC) flyback designs without needing an external clamping snubber for reflected voltage spikes. The 20 W power rating is the practical ceiling for a single-switch flyback in this package — expect to derate for ambient temperature above 85°C or for tight enclosure airflow. At 60 kHz fixed frequency, the transformer core size and EMI filter components land in a familiar sweet spot: small enough for a compact EE16 or EFD20 core, but not so high that the switching losses dominate the thermal budget.
Built-in fault protections reduce external supervision
The controller integrates current limiting, over-temperature shutdown, and over-voltage protection on the Vcc pin. That means you can skip the external comparator and optocoupler feedback for basic protection — the chip handles hiccup-mode restart on its own. The start-up voltage threshold is 14 V, and the supply range runs from 8.5 V to 23.5 V, which gives the bias winding plenty of margin to keep the IC alive under load transients.
Temperature grade and package — storage and reflow notes
Store the reels dry.
It is ROHS3 compliant.