The working principle of the switching power supply chip is:
1. The AC power input is rectified and filtered into DC;
2. The switch tube is controlled by the high-frequency PWM(pulse width modulation) signal, and the DC is added to the switching transformer primary;
3. Switching transformer secondary induction of high-frequency voltage, through the rectification filter to supply load;
4. The output part is fed back to the control circuit through a certain circuit to control the PWM duty cycle to achieve the purpose of stable output.