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US 10,833,578 B2Granted
Circuit and method for jitter generation in quasi-resonant converter
AssigneeDiodes Incorporated
InventorWei Chuan Su
Life of this patent
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Abstract
A Quasi-Resonant (QR) converter includes a power switch controlling the primary current flow and a time-varying capacitance coupled in parallel to the power switch. The time-varying capacitance is configured to add a frequency jitter to the frequency switch of the converter.
Claims20
A Quasi-Resonant (QR) converter, comprising:
- a transformer having a primary winding for coupling to an external input voltage, a secondary winding providing an output voltage of the converter, and an auxiliary winding for providing a sensing signal, which monitors a resonant waveform of the converter during discontinuous time;
- a power switch for coupling to the primary winding of the converter to control a primary current flow;
- a capacitor and a modulation switch coupled in parallel to the power switch, the modulation switch being coupled in series with the capacitor;
- and
- a control circuit, comprising:
- a quasi-resonant controller for turning on the power switch at a valley point of the resonant waveform in the sensing signal during a discontinuous time;
- and
- a jitter controller for turning on the modulation switch at a peak point of the resonant waveform in the sensing signal during the discontinuous time, wherein the jitter controller varies a turn-on time of the modulation switch to add a frequency jitter to a switching frequency of the converter.
5 more elements
A control circuit for a quasi-resonant (QR) converter, comprising:
- a quasi-resonant controller for turning on a power switch at a valley point of a resonant waveform in a sensing signal during a discontinuous time of the converter, wherein the power switch is coupled to a primary winding of the converter to control a primary current flow, and the sensing signal monitors the resonant waveform of the converter through an auxiliary winding;
- and
- a jitter controller for adding a capacitance in parallel to the power switch at a peak point of the resonant waveform in the sensing signal during the discontinuous time, wherein the jitter controller varies an oscillation period of the resonant waveform to add a frequency jitter to a switching frequency of the converter.
A method for controlling a quasi-resonant (QR) converter, comprising:
- turning on a power switch at a valley point of a resonant waveform in a sensing signal during a discontinuous time of the converter, wherein the power switch is coupled to a primary winding of the converter to control a primary current flow, and the sensing signal monitors the resonant waveform of the converter through an auxiliary winding;
- and
- adding a capacitance in parallel to the power switch at a peak point of the resonant waveform in the sensing signal during the discontinuous time, to vary an oscillation period of the resonant waveform to add a frequency jitter to a switching frequency of the converter.
Dependencies are inferred from the claim text.