Output current control circuit for power converter with a changeable switching frequency
First Claim
1. An output current control circuit for a power converter, comprising:
- a current-detection circuit, coupled to a current sense device, for generating a primary-current signal in response to a primary-side switching current of a transformer;
a voltage-detection circuit, coupled to the transformer, for generating a period signal and a discharge-time signal in response to a reflected voltage of the transformer;
a signal-process circuits, for generating a current signal in response to the primary-current signal, the period signal and the discharge-time signal;
a switching control circuit, coupled to the signal-process circuit, for generating a switching signal in response to the current signal; and
a pulse generator, coupled to the voltage-detection circuit, for generating a sample-pulse signal in response to the period signal,wherein the switching signal is utilized to switch the transformer and regulate the output current of the power converter;
the period signal is correlated to the switching period of the switching signal, the discharge-time signal is correlated to the duty cycle of a secondary-side switching current of the transformer;
the current signal is correlated to the output current of the power converter;
the sample-pulse signal is used to control sampling of the signal-process circuit.
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Abstract
A control circuit controls the output current of the power converter at the primary side of the transformer. The control circuit includes a current-detection circuit for generating a primary-current signal in response to the switching current of the transformer. A voltage-detection circuit is coupled to the transformer to generate a period signal and a discharge-time signal in response to the reflected voltage of the transformer. A signal-process circuit is utilized to generate a current signal in response to the primary-current signal, the period signal and the discharge-time signal. The period signal is correlated to the switching period of the switching signal of the power converter. The discharge-time signal is correlated to the duty cycle of switching current at the secondary-side of the transformer. The current signal is correlated to the output current of the power converter.
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Citations
10 Claims
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1. An output current control circuit for a power converter, comprising:
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a current-detection circuit, coupled to a current sense device, for generating a primary-current signal in response to a primary-side switching current of a transformer; a voltage-detection circuit, coupled to the transformer, for generating a period signal and a discharge-time signal in response to a reflected voltage of the transformer; a signal-process circuits, for generating a current signal in response to the primary-current signal, the period signal and the discharge-time signal; a switching control circuit, coupled to the signal-process circuit, for generating a switching signal in response to the current signal; and a pulse generator, coupled to the voltage-detection circuit, for generating a sample-pulse signal in response to the period signal, wherein the switching signal is utilized to switch the transformer and regulate the output current of the power converter;
the period signal is correlated to the switching period of the switching signal, the discharge-time signal is correlated to the duty cycle of a secondary-side switching current of the transformer;
the current signal is correlated to the output current of the power converter;
the sample-pulse signal is used to control sampling of the signal-process circuit. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An output current detection circuit for a power converter, comprising:
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a current-detection circuit, for generate a primary-current signal in response to a switching current of a transformer; a voltage-detection circuit, coupled to the transformer, for generating a period signal and a discharge-time signal; a signal-process circuits for generating a current signal in response to the primary-current signal, the period signal and the discharge-time signal; and a pulse generator, coupled to the voltage-detection circuit, for generating a sample-pulse signal in response to the period signal, wherein the power converter includes a switching signal for switching the transformer and regulating the output of the power converter;
the period signal is correlated to the switching period of the switching signal, the discharge-time signal is correlated to the demagnetizing period of the transformer, and the current signal is correlated to the output current of the power converter;
the sample-pulse signal is used to control sampling of the signal-process circuit. - View Dependent Claims (8, 9, 10)
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Specification