Switching control circuit for primary-side controlled power converters
First Claim
1. A switching control circuit for a primary-side controlled power converter, comprising:
- a switching device, for switching a transformer, wherein said transformer is supplied with an input voltage of the power converter;
a switching signal, controlling said switching device for regulating an output voltage and a maximum output current of the power converter; and
a controller, coupled to said transformer and a current-sense device to generate a voltage-feedback signal and a current-feedback signal by sampling a voltage signal and a discharge time of said transformer during an off-time of said switching signal, and measuring a current signal of said transformer during an on-time of said switching signal, wherein said switching signal is generated in response to said voltage-feedback signal and said current-feedback signal.
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Abstract
The present invention discloses a switching control circuit for a primary-side controlled power converter. A voltage-waveform detector produces a voltage-feedback signal and a discharge-time signal. A current-waveform detector generates a current-waveform signal by measuring a primary-side switching current. An integrator generates a current-feedback signal by integrating the current-waveform signal with the discharge time. A time constant of the integrator is correlated with the switching frequency, thus the current-feedback signal is proportional to an output current of the power converter. A PWM circuit controls the pulse width of the switching signal in response to the outputs of a voltage-loop error amplifier and a current-loop error amplifier. The output voltage and the maximum output current of the power converter are therefore regulated.
141 Citations
17 Claims
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1. A switching control circuit for a primary-side controlled power converter, comprising:
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a switching device, for switching a transformer, wherein said transformer is supplied with an input voltage of the power converter; a switching signal, controlling said switching device for regulating an output voltage and a maximum output current of the power converter; and a controller, coupled to said transformer and a current-sense device to generate a voltage-feedback signal and a current-feedback signal by sampling a voltage signal and a discharge time of said transformer during an off-time of said switching signal, and measuring a current signal of said transformer during an on-time of said switching signal, wherein said switching signal is generated in response to said voltage-feedback signal and said current-feedback signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A switching control circuit for a primary-side controlled power converter, comprising:
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a switching device, for switching a transformer, wherein said transformer is supplied with an input voltage of the power converter; a switching signal, controlling said switching device for regulating an output voltage of the power converter; and a controller, coupled to said transformer to generate a voltage-feedback signal by multi- sampling a voltage signal and a discharge time of said transformer during an off-time of said switching signal, wherein said switching signal is generated in response to said voltage-feedback signal. - View Dependent Claims (15, 16, 17)
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Specification