Working process of switching power supply is fairly easy to understand, linear power supply, so that the power transistor operating in the linear mode, and the linear power is different, PWM switching power supply is working to make the power transistor is turned on and off in the state, in both state, applied to the power transistor volt - Ann product is very small (when turned on, voltage is low, current is large; shutdown, high voltage, low current) VA / power devices is the product of a power semiconductor the device produced loss.
Compared with the linear power, PWM switching power supply is more efficient working process by "chopping", i.e., cut into a DC voltage amplitude of the input pulse voltage equal to the input voltage magnitude to achieve. Pulse duty cycle by switching power supply controller to adjust. Once the input AC voltage is cut into a square wave, the amplitude can be raised or lowered by a transformer. By increasing the number of secondary winding of the transformer can increase the value of the output voltage. Finally, these AC waveform rectified DC output voltage obtained after filtering.