Control circuit and method therefor
AssigneeSemiconductor Components Industries, LLC
InventorsChen-Hua CHIU, Guang-Chao ZHANG, Mao-Sheng LIN, HyeongSeok BAEK
Life of this patent
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Abstract
In one embodiment, a control circuit may be configured to form a switching signal to switch a power transistor at a frequency to regulate an output voltage of the power supply to a target value wherein the control circuit is configured to operate in a normal operating mode and a start-up mode and wherein the control circuit is configured to switch the switching signal at a target frequency in response to operating in the normal operating mode. A first circuit may be configured to control the frequency of the switching signal to increase from a first frequency to a second frequency that is less than the target frequency in response to operating in the start-up mode.
Claims20
A control circuit for a power supply comprising:
- the control circuit configured to operate a switching signal at a frequency to switch a power switch and to regulate an output voltage to a target value;
- an oscillator configured to form an oscillator signal at the frequency, and to cause the switching signal to switch at the frequency;
- and
- a first circuit configured to control the frequency of the oscillator signal to increase during a start-up sequence initiated by the control circuit wherein the control circuit terminates increasing the frequency in response to regulating the output voltage to the target value.
A method of forming a control circuit for a power supply comprising:
- forming the control circuit to form a switching signal to switch a power switch to regulate an output voltage to a target value;
- forming a variable frequency oscillator to oscillate at a frequency wherein the control circuit switches the switching signal at a target frequency in response to the output voltage having the target value;
- and
- forming a first circuit to initiate increasing the frequency from a first frequency that is less than the target frequency to a second frequency, that is greater than the first frequency and is also less than the target frequency, responsively to the control circuit operating in a start-up mode wherein the first circuit is configured to continue increasing the frequency until the output voltage reaches substantially the target value.
A method of forming a power supply control circuit comprising:
- forming a control circuit to form a switching signal to switch a power transistor at a frequency to regulate an output voltage of the power supply to a target value wherein the control circuit is configured to operate in a normal operating mode and a start-up mode and wherein the control circuit is configured to switch the switching signal at a target frequency in response to operating in the normal operating mode;
- and
- configuring a first circuit to control the frequency of the switching signal to increase from substantially a first frequency to a second frequency that is less than the target frequency in response to operating in the start-up mode.
Dependencies are inferred from the claim text.