Switching power supply circuit diagram composed of FA500

The figure shows a switching power supply composed of FA550O . The input AC voltage is 100V and the output is 16V/2.5A. FA5500 integrated controller , its output OUT (⑦ pin) drives the gate of the power M0S-FET (VF1) through the resistor R2. R3 and R14 are the overcurrent detection resistors of VF1. VF1 performs switching operation, causing a pulse-like current to flow through the winding N1 of its transformer T1. C3 is the resonant capacitor , and C4 is the capacitor that reduces the output impedance. The output voltage of the winding is rectified and smoothed by VD10 and C5 into the output DC voltage.

VF2 and VD11 form an output voltage detection circuit . The output voltage is divided by R12 and R11 and sent to the voltage detection circuit . The collector output of VF2 is supplied to the oscillation circuit composed of L7, C19, G1, etc. through R10 . C13 is a bypass capacitor , and VS1 is a Zener diode to prevent overvoltage from being added to the oscillation circuit .