Analog Devices website (free). VIPER models available from ST’s website.
Modern VIPer-based designs, such as the series, incorporate advanced features that these software tools help optimize: VIPer - STMicroelectronics viper flyback converter design software download better
(Resistor-Capacitor-Diode) across the primary winding to protect the VIPer MOSFET from voltage spikes. Optocoupler & TL431: Analog Devices website (free)
You can run thermal simulations and stability analysis before ever soldering a component. such as the series