Power switching circuit overload detection tube

Power switching tube overload detection circuit comprising a logic circuit driving power output terminal of the NMOS transistor control terminal connected to the logic circuit includes a PWM drive signal generator and a direct drive power to the inverter and the NMOS gate connection form a first PMOS transistor and a first NMOS transistor, the drain terminal of the first PMOS transistor and a first NMOS transistor as an output terminal of the logic driver circuit; output terminal of the logic circuit is also connected to the drive pull-down branch. Power switching power supply according to the present invention, a pipe overload detection circuit, by the gate control signal and detecting the zero crossing can be realized and the resonance inductor current valley detection, eliminating the need for a plurality of peripheral elements and a pin of the chip to reduce significantly reducing the cost of the chip and the power supply system.