5V/2A Isolated Switching Power Supply Schematic

The switch circuit as shown below: C1 is the input filter capacitance, VDz, and VD1 primary side clamp protection circuit. R1 for the control of the end resistance, C2 is a bypass capacitor. Parallel between the end of S-TOP414GC-C10 is to prevent high-frequency interference in the control side, sometimes caused by trigger power-off circuit malfunction. VD2 output rectifier diode, C3, C4, and L,, C5, and C6 constitute the output filter, C9 denoising output capacitance. The external error amplifier consists of the shunt regulatorTL431. When the output voltage fluctuations, R3, and R4, the partial pressure of the sample voltage with the reference voltage of the TL431, an external control signal, through the optocoupler PC817A the change TOP414G control terminal current, and adjusts the duty ratio Uo tend stability. The control loop gain is set by R2. The feedback winding voltage VD3, and C7 rectifier filter, the infrared receiver thePC817Ain the tube power supply.




Source: http://www.hqew.net/circuit-diagram/5V$2f2A-Isolated-Switching-Power-Supply-Schematic_2394.html