Power conversion efficiency using variable switching frequency
A power conversion circuit is provided. An input of the power conversion circuit is coupled to a first voltage potential. A switching frequency of the power conversion circuit is set based on a magnitude of the first voltage potential.
1. A semiconductor device for controlling a power conversion circuit which includes an input coupled for receiving an input voltage and an output providing an output voltage, the semiconductor device comprising:
an input terminal adapted for receiving the input voltage;
a voltage sensing circuit coupled to the input terminal; and
a controller coupled to an output of the voltage sensing circuit and configured to set a first switching frequency of the controller in response to a first value of the input voltage and set a second switching frequency of the controller less than the first switching frequency in response to a second value of the input voltage being less than the first value of the input voltage.
2. The semiconductor device of claim 1 , wherein the first value of the input voltage is a high line voltage and the second value of the input voltage is a low line voltage.
3. The semiconductor device of claim 1 , wherein the first switching frequency of the controller is proportional to the first value of the input voltage and the second switching frequency of the controller is proportional to the second value of the input voltage.
4. The semiconductor device of claim 1 , wherein the controller is configured for setting the first switching frequency and second switching frequency of the controller based on an output current of the power conversion circuit.
5. The semiconductor device of claim 1 , wherein the controller includes an output providing a control signal operating at the first switching frequency or second switching frequency.
6. The semiconductor device of claim 1 , wherein the power conversion circuit is an active clamp flyback converter.
7. A power conversion circuit including an input terminal coupled for receiving an input voltage and an output terminal providing an output voltage, the power conversion circuit comprising a controller coupled to the input terminal for receiving the input voltage, wherein the controller is configured to set a first switching frequency of the controller in response to the input voltage being greater than a threshold and set a second switching frequency of the controller less than the first switching frequency in response to the input voltage being less than the threshold, where the switching frequency is used to convert from the input voltage to the output voltage.
8. The power conversion circuit of claim 7 , wherein the input voltage is a high line voltage or a low line voltage.
9. The power conversion circuit of claim 7 , wherein the first switching frequency and second switching frequency are proportional to the input voltage.
10. The power conversion circuit of claim 7 , wherein the controller is configured for setting the first switching frequency and second switching frequency of the controller based on an output current of the power conversion circuit.
11. The power conversion circuit of claim 7 , wherein the controller is configured for sensing the input voltage.
12. The power conversion circuit of claim 7 , wherein the controller includes an output providing a control signal operating at the first switching frequency or second switching frequency.
13. The power conversion circuit of claim 7 , wherein the power conversion circuit is an active clamp flyback converter.
14. The power conversion circuit of claim 7 , further including a voltage sensing circuit coupled to the input terminal of the power conversion circuit for providing the input voltage to the controller.
15. A method of making a semiconductor device for a power conversion circuit which includes an input terminal coupled for receiving an input voltage and an output terminal providing an output voltage, comprising:
providing a controller adapted for coupling to the input terminal for receiving the input voltage;
determining a target value for a magnetizing current through a transformer of the power conversion circuit;
sensing the input voltage and providing the input voltage to the controller; and
setting a switching frequency of the controller to maintain the target value of the magnetizing current given the input voltage.
16. The method of claim 15 , wherein the input voltage is a high line voltage or a low line voltage.
17. The method of claim 15 , wherein the switching frequency of the controller is proportional to the input voltage.
18. The method of claim 15 , wherein the controller sets the switching frequency of the controller based on an output current of the power conversion circuit.
19. The method of claim 15 , wherein the controller includes an output providing a control signal operating at the switching frequency.
20. The method of claim 15 , wherein the power conversion circuit is an active clamp flyback converter.
21. A method of making a semiconductor device for a power conversion circuit which includes an input terminal coupled for receiving an input voltage and an output terminal providing an output voltage, comprising:
providing a controller adapted for coupling to the input terminal for receiving the input voltage;
determining a magnetizing current through a transformer of the power conversion circuit;
sensing the input voltage; and
setting a switching frequency of the controller to maintain a constant value for the magnetizing current given the input voltage.
22. The method of claim 21 , wherein the input voltage is a high line voltage or a low line voltage.
23. The method of claim 21 , wherein the switching frequency of the controller is proportional to the input voltage.
24. The method of claim 21 , wherein the controller sets the switching frequency of the controller based on an output current of the power conversion circuit.
25. The method of claim 21 , wherein the controller includes an output providing a control signal operating at the switching frequency.