Frequency control circuit, control method and switching converter
First Claim
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1. A frequency control circuit applied in a switching converter, wherein said frequency control circuit is configured to:
- a) regulate an off time of a power transistor of said switching converter in one switching cycle according to an on time of said power transistor, or regulate said on time of said power transistor in one switching cycle according to said off time of said power transistor; and
b) maintain an operating frequency of said switching converter to be within a predetermined range by a state switching circuit configured to have a plurality of operating states, wherein each operating state has a predetermined off/on time of said power transistor, and said plurality of operating states are switched according to said on/off time of said power transistor in a present cycle, in order to select a matched off/on time of said power transistor.
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Abstract
A frequency control circuit, applied in a switching converter, can be configured to: regulate an off time of a power transistor of the switching converter in one switching cycle according to an on time of the power transistor, or regulate the on time of the power transistor in one switching cycle according to the off time of the power transistor; and maintain an operating frequency of the switching converter to be within a predetermined range.
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Citations
15 Claims
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1. A frequency control circuit applied in a switching converter, wherein said frequency control circuit is configured to:
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a) regulate an off time of a power transistor of said switching converter in one switching cycle according to an on time of said power transistor, or regulate said on time of said power transistor in one switching cycle according to said off time of said power transistor; and b) maintain an operating frequency of said switching converter to be within a predetermined range by a state switching circuit configured to have a plurality of operating states, wherein each operating state has a predetermined off/on time of said power transistor, and said plurality of operating states are switched according to said on/off time of said power transistor in a present cycle, in order to select a matched off/on time of said power transistor. - View Dependent Claims (2, 3, 4, 5)
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6. A method of controlling a frequency of a switching converter, the method comprising:
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a) regulating an off time of a power transistor of said switching converter in one switching cycle according to an on time of said power transistor, or regulating said on time of said power transistor in one switching cycle according to said off time of said power transistor; b) maintaining an operating frequency of said switching converter to be within a predetermined range; c) presetting a plurality of operating states, wherein each operating state has a predetermined off/on time of said power transistor; and d) switching between said plurality of operating states according to said on/off time of said power transistor in a present cycle, in order to select a matched off/on time of said power transistor. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification