概要

This board implements a 4 W single-output wide range mains power supply set in flyback isolated topology, using the VIPER16LN, an off-line high voltage converter by STMicroelectronics. The features include an 800 V avalanche rugged power section, PWM operation at 60 kHz with frequency jittering for lower EMI, current limiting with adjustable set point, on-board soft-start, a safe auto-restart after a fault condition and a low stand-by power.
The device does not require a biasing circuit to operate because the IC can be supplied by an internal current generator, therefore saving the cost of the transformers auxiliary winding. If the device is biased through an auxiliary winding, the demonstration board can reach very low standby consumption (< 30 mW at 230 V_AC, with output load disconnected).
The IC implements several protections that considerably increase end-product safety and reliability: thermal shutdown with hysteresis, delayed overload protection, open loop failure protection (the last one available only if the device is biased through the auxiliary winding).