Small power switching power supply circuit

Small power switching power supply circuit

Shown is a low-power switching power supply circuit , suitable for AC adapters, battery chargers, auxiliary power supplies (USB),
instruments and other circuits. The circuit is mainly
composed of 220V AC input circuit, rectifier filter circuit, PWM control circuit (NCP1200), reverse peak pulse absorption circuit, switching transformer and secondary output circuit.
    AC 220 V outputs about 300 V DC voltage through the bridge rectifier stack, which is added to the drain of the switching field effect transistor through the primary winding of the switching transformer T1.
At the same time, it provides voltage to the switching oscillation integrated circuit NCP1200@ pin, and NCP1200 starts to oscillate. The pin outputs switching pulses
and drives the field effect transistor to output an oscillation signal. After oscillation, the switching transformer outputs, and then outputs 6.5 V DC voltage after rectification and filtering.