Power converter circuitry with improved control scheme
A method of operating a switching power converter includes operating the switching power converter in a boundary conduction mode when a switching frequency of a switch in the switching power converter is below a switching frequency threshold such than an on time of the switch is adjusted based on a desired output power of the switching power converter, and operating the switching power converter in a discontinuous conduction mode when the switching frequency of the switch is above the switching frequency threshold such that one or more of the on time of the switch and a switching period of the switch are adjusted based on the desired output power of the switching power converter and the on time of the switch is clamped at a minimum switch on time.
1. Control circuitry for a switching power converter comprising:
processing circuitry; and
a memory storing instructions which, when executed by the processing circuitry cause the control circuitry to:
provide a power converter control signal to the switching power converter in order to operate the switching power converter in a boundary conduction mode when a switching frequency of a switch in the switching power converter is below a switching frequency threshold such that an on time of the switch is adjusted based on a desired output power of the switching power converter; and
provide the power converter control signal to the switching power converter in order to operate the switching power converter in a discontinuous conduction mode when the switching frequency of the switch is above the switching frequency threshold such that one or more of the on time of the switch and a switching period of the switch are adjusted based on the desired output power of the switching power converter and the on time of the switch is clamped at a minimum switch on time.
2. The control circuitry of claim 1 wherein the control circuitry is configured to provide the power converter control signal to the switching power converter in order to operate the switching power converter in the discontinuous conduction mode such that:
when the on time of the switch is above a switch on time threshold, the on time of the switch is adjusted based on the desired output of the switching power converter;
when the on time of the switch is below the on time threshold and above the minimum switch on time, the on time of the switch and the switching period of the switch are adjusted based on the desired output power of the switching power converter; and
when the on time of the switch is equal to or below the minimum switch on time, the on time of the switch is clamped at the minimum switch on time and the switching period of the switch is adjusted based on the desired output power of the switching power converter.
3. The control circuitry of claim 2 wherein the switch is formed from a semiconductor material with a bandgap greater than 2 eV.
4. The control circuitry of claim 2 wherein the switching frequency threshold is between 800 kHz and 1 MHz.
5. The control circuitry of claim 4 wherein the minimum switch on time is between 80 ns and 120 ns.
6. The control circuitry of claim 5 wherein the on time threshold is between 145 ns and 185 ns.
7. Power converter circuitry comprising:
a switching power converter comprising a switch and configured to receive a power supply signal and provide an output power signal; and
control circuitry coupled to the switch and comprising:
processing circuitry; and
a memory storing instructions which, when executed by the processing circuitry cause the control circuitry to:
provide a power converter control signal to the switch in order to operate the switching power converter in a boundary conduction mode when a switching frequency of the switch in the switching power converter is below a switching frequency threshold such that an on time of the switch is adjusted based on a desired output power of the switching power converter; and
provide the power converter control signal to the switch in order to operate the switching power converter in a discontinuous conduction mode when the switching frequency of the switch is above the switching frequency threshold such that one or more of the on time of the switch and a switching period of the switch are adjusted based on the desired output power of the switching power converter and the on time of the switch is clamped at a minimum switch on time.
8. The power converter circuitry of claim 7 wherein the control circuitry is configured to provide the power converter control signal to the switch in order to operate the switching power converter in the discontinuous conduction mode such that:
when the on time of the switch is above a switch on time threshold, the on time of the switch is adjusted based on the desired output of the switching power converter;
when the on time of the switch is below the switch on time threshold and above the minimum switch on time, the on time of the switch and the switching period of the switch are adjusted based on the desired output power of the switching power converter; and
when the on time of the switch is equal to or below the minimum switch on time, the on time of the switch is clamped at the minimum switch on time and the switching period of the switch is adjusted based on the desired output power of the switching power converter.
9. The power converter circuitry of claim 8 wherein the switching power converter is a single-ended primary-inductor converter (SEPIC).
10. The power converter circuitry of claim 9 wherein the switch is formed from a semiconductor material with a bandgap greater than 2 eV.
11. The power converter circuitry of claim 8 wherein the switching frequency threshold is between 800 kHz and 1 MHz.
12. The power converter circuitry of claim 11 wherein the minimum switch on time is between 80 ns and 120 ns.
13. The power converter circuitry of claim 12 wherein the on time threshold is between 145 ns and 185 ns.
14. The power converter circuitry of claim 8 wherein the output power signal is configured to drive one or more light-emitting diodes (LEDs).
15. A method of operating a switching power converter comprising:
operating the switching power converter in a boundary conduction mode when a switching frequency of a switch in the switching power converter is below a switching frequency threshold such that an on time of the switch is adjusted based on a desired output power of the switching power converter; and
operating the switching power converter in a discontinuous conduction mode when the switching frequency of the switch is above the switching frequency threshold such that one or more of the on time of the switch and a switching period of the switch are adjusted based on the desired output power of the switching power converter and the on time of the switch is clamped at a minimum switch on time.
16. The method of claim 15 wherein the switching power converter is operated in the discontinuous conduction mode such that:
when the on time of the switch is above a switch on time threshold, the on time of the switch is adjusted based on the desired output power of the switching power converter;
when the on time of the switch is below the on time threshold and above the minimum switch on time, the on time of the switch and the switching period of the switch are adjusted based on the desired output power of the switching power converter; and
when the on time of the switch is equal to or below the minimum switch on time, the on time of the switch is clamped at the minimum switch on time and the switching period of the switch is adjusted based on the desired output power of the switching power converter.
17. The method of claim 16 wherein the switch is formed from a semiconductor material with a bandgap greater than 2 eV.
18. The method of claim 16 wherein the switching frequency threshold is between 800 kHz and 1 MHz.
19. The method of claim 18 wherein the minimum switch on time is between 80 ns and 120 ns.
20. The method of claim 19 wherein the on time threshold is between 145 ns and 185 ns.