The NCP1365 offer a new solution targeting output power levels from a few watts up to 20 W in a universal-mains flyback application.Thanks to a novel method this new controller eliminates the need for a secondary feedback circuitry (typically an opto-coupler and TL431 reference) while achieving excellent line and load regulation.The NCP1365 operates in valley lockout quasi-resonant peak current mode control mode at high load to provide high efficiency. When the power on the secondary side starts to diminish, the controller automatically adjusts the duty-cycle then at lower load the controller enters in pulse frequency modulation at fixed peak current with a valley switching detection. This technique allows keeping the output regulation with tiny dummy load. Valley lockout at the first 4 valleys prevent valley jumping operation and then a valley switching at lower load provides high efficiency.