Circuit analysis of LED power controller with PFC flyback

1. AC input mains voltage sampling voltage dividing resistor for PFC control;

2. AC input mains current sampling resistor for PFC control;

3. Rectifier output filter capacitor;

4. Input current limiting resistor;

5. External power MOSFET switch gate drive current limiting resistor;

6. Feedback isolation photocoupler;

7. Optocoupler operating current temperature compensation resistor NTC1;

8. Load current constant current error current amplifier;

9. Flyback transformer has input and output isolation function;

10. Load current sampling resistor, load current sampling voltage signal is sent to the inverting input terminal of error amplifier U2;

11. The capacity of the output filter capacitor is related to the load ripple current. The larger the capacity, the smaller the equivalent series resistance (ESR), and the smaller the output load ripple current;

12. Y capacitor has input and output EMI filtering and isolation functions.