METHOD AND APPARATUS FOR A CONTROL CIRCUIT WITH MULTIPLE OPERATING MODES
First Claim
1. A controller for use in a power converter that includes a switch, the controller comprising:
- an input terminal to be coupled to receive a feedback signal representative of an output of the power converter;
an oscillator configured to generate a first signal to determine a duration of a switching cycle period of the switch; and
a logic circuit coupled to the input terminal and to the oscillator, wherein the logic circuit is configured to generate a second signal to control switching of the switch to regulate power delivered to the output of the power converter in response to the feedback signal and in response to the first signal, wherein the logic circuit is configured to generate the second signal to control a peak switch current of the switch during the switching cycle period according to either a first mode of operation or a second mode of operation, wherein the logic circuit is configured to vary the peak switch current of the switch in the first mode of operation in response to the feedback signal indicating that an output load is greater than a threshold and, wherein the logic circuit is configured to keep the peak switch current of the switch at a substantially constant value in the second mode of operation in response to the feedback signal indicating that the output load is less than the threshold.
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Abstract
A controller for use in a power converter includes an oscillator that generates a first signal that determines a duration of a switching cycle period of a switch included in the power converter. The controller also includes a logic circuit that generates a second signal to control switching of the switch in response to a feedback signal and in response to the first signal. The logic circuit generates the second signal to control a peak switch current of the switch during each switching cycle period according to either a first mode of operation or a second mode of operation. The peak switch current of the switch is varied in the first mode of operation in response to the feedback signal indicating that an output load is greater than a threshold and the peak switch current of the switch is kept at a constant value in the second mode of operation in response to the feedback signal indicating that the output load is less than the threshold.
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Citations
8 Claims
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1. A controller for use in a power converter that includes a switch, the controller comprising:
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an input terminal to be coupled to receive a feedback signal representative of an output of the power converter; an oscillator configured to generate a first signal to determine a duration of a switching cycle period of the switch; and a logic circuit coupled to the input terminal and to the oscillator, wherein the logic circuit is configured to generate a second signal to control switching of the switch to regulate power delivered to the output of the power converter in response to the feedback signal and in response to the first signal, wherein the logic circuit is configured to generate the second signal to control a peak switch current of the switch during the switching cycle period according to either a first mode of operation or a second mode of operation, wherein the logic circuit is configured to vary the peak switch current of the switch in the first mode of operation in response to the feedback signal indicating that an output load is greater than a threshold and, wherein the logic circuit is configured to keep the peak switch current of the switch at a substantially constant value in the second mode of operation in response to the feedback signal indicating that the output load is less than the threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification