The NCP1336 hosts a high-performance circuitry aimed to powering quasi-resonant converters. Capitalizing on a novel valley-lockout system, the controller shifts gears and reduces the switching frequency as the power loading becomes lighter. This results in a stable operation despite switching events always occurring in the drain-source valley. This system works down to the 4th valley and toggles to a variable frequency mode beyond, ensuring an excellent standby power performance. The controller takes benefit of a high-voltage start-up current source to provide a quick and lossless power-on sequence. To improve the safety in overload situations, the controller includes an Over Power Protection circuit which clamps the delivered power at high-line. Safety-wise, an adjustable timer relies on the feedback voltage to detect a fault. On version B, this fault triggers a triple-hiccup on the VCC pin which naturally reduces the average input power drawn by the converter. On version A, when a fault is detected, the controller is latched-off. Particularly well suited for adapter applications, the controller features two latch inputs: one dedicated to Over Temperature protection (OTP) which offers an easy means to connect a pull-down temperature sensor like an NTC, and a second one more classical that can be used ot performa an accurate Over voltage Protection. Finally, a brownout pin whcih stops the circuit operation in presence of a low mains condition is included.