Control circuit for switch-mode power supply, power circuit, and electronic device
A control circuit for a switch-mode power supply, a power circuit, and an electronic device. The control circuit outputs a control signal to control a switching frequency of the switch-mode power supply. The control circuit adjusts, in a plurality of cycles, a frequency of the control signal based on a plurality of ranges, and controls, in each cycle, the frequency of the control signal to change with time in a range corresponding to each cycle. In the embodiments, a frequency-domain energy dispersion degree of the control signal output by the control circuit can be increased, electromagnetic interference generated by the control signal output by the control circuit is reduced, and finally, it is ensured that the power circuit and the electronic device including the power circuit can pass a related security test.
1 . A control circuit for a switch-mode power supply, wherein the control circuit is configured to:
output a control signal to control a switching frequency of a switching device in the switch-mode power supply;
adjust, in a plurality of cycles, a frequency of the control signal based on a plurality of ranges;
control, in each cycle of the plurality of cycles, the frequency of the control signal to change with time in a range of the plurality of ranges corresponding to each cycle, wherein at least one of a random duration of a reference cycle and a reference range restricts the change with time; and
adjust a duration of at least one cycle of the plurality of cycles based on a random number corresponding to the at least one cycle of the plurality of cycles and the random duration of the reference cycle.
2 . The control circuit according to claim 1 , wherein a duration of at least one cycle of the plurality of cycles is random.
3 . The control circuit claim 1 , wherein the control circuit is further configured to:
adjust a duration of at least one cycle of the plurality of cycles, wherein the duration of the at least one cycle is less than or greater than that a duration of a previous cycle.
4 . The control circuit according to claim 1 , wherein the control circuit is further configured to:
randomly adjust a duration of at least one cycle of the plurality of cycles.
5 . The control circuit according to claim 1 , wherein the control circuit is further configured to:
adjust an amplitude of at least one range of the plurality of ranges, wherein the amplitude of the at least one range is less than or greater than that an amplitude of a previous range.
6 . The control circuit according to claim 1 , wherein the control circuit is further configured to:
adjust an amplitude of at least one range of the plurality of ranges to be greater than 90% of an amplitude of the reference range and less than the amplitude of the reference range.
7 . The control circuit according to claim 1 , wherein the control circuit is further configured to:
adjust an amplitude of least one range based on a random number corresponding to at least one cycle of the plurality of cycles and the reference range.
8 . A power circuit, comprising:
a switch-mode power supply, wherein the switch-mode power supply comprises at least one switching device; and
a control circuit that is configured to:
output a control signal to control a switching frequency of the switching device, the switching frequency of the switching device changes in a plurality of cycles based on a plurality of ranges, in each cycle of the plurality of cycles, the switching frequency of the switching device changes with time in a range corresponding to each cycle, and at least one of a duration of a reference cycle and a reference range restricts the change with time, and
adjust a duration of at least one cycle of the plurality of cycles based on a random number corresponding to the at least one cycle of the plurality of cycles and the duration of the reference cycle.
9 . The power circuit according to claim 8 , wherein the control circuit further comprises:
a clock source configured to generate a clock signal; and
a modulator configured to generate the control signal after modulating the clock signal in the plurality of cycles based on the plurality of ranges.
10 . The power circuit according to claim 8 , wherein at least one of a duration of at least one cycle of the plurality of cycles and an amplitude of at least one range of the plurality of ranges is random.
11 . The power circuit according to claim 8 , wherein a duration of at least one cycle of the plurality of cycles is less than or greater than that of a previous cycle.
12 . The power circuit according to claim 8 , wherein an amplitude at which the switching frequency of the switching device changes with time in at least one cycle of the plurality of cycles is less than or greater than an amplitude at which the switching frequency of the switching device changes with time in a previous cycle.
13 . The power circuit according to claim 8 , wherein the switch-mode power supply further comprises a boost circuit.
14 . The power circuit according to claim 8 , wherein the switch-mode power supply further comprises an asymmetrical half-bridge flyback conversion circuit that includes a half-bridge circuit and a transformer.
15 . An electronic device, comprising:
a power circuit, wherein the power circuit comprises a switch-mode power supply and a control circuit, wherein the switch-mode power supply comprises at least one switching device, the control circuit is configured to:
output a control signal to control a switching frequency of the switching device, the switching frequency of the switching device changes in a plurality of cycles based on a plurality of ranges, in each cycle of the plurality of cycles, the switching frequency of the switching device changes with time in a range of the plurality of ranges corresponding to each cycle, and at least one of a duration of a reference cycle and a reference range restricts the change with time, and
adjust a duration of at least one cycle of the plurality of cycles based on a random number corresponding to the at least one cycle of the plurality of cycles and the duration of the reference cycle.
16 . The control circuit according to claim 1 , wherein an amplitude of at least one range of the plurality of ranges is random.
17 . The control circuit according to claim 1 , wherein the control circuit is further configured to:
adjust an amplitude of at least one range of the plurality of ranges to be greater than an amplitude of a reference range and less than 110% of the amplitude of the reference range.
18 . The power circuit according to claim 8 , wherein the switch-mode power supply further comprises a buck circuit.
19 . The power circuit according to claim 8 , wherein the switch-mode power supply further comprises a buck-boost circuit.