AUDIBLE NOISE SUPPRESSION IN A RESONANT SWITCHING POWER CONVERTER
First Claim
1. A resonant switching power circuit, comprising:
- a resonant circuit including at least one inductance and at least one capacitance for transferring energy to an output of the resonant switching power circuit;
a switching circuit coupled to the resonant circuit for transferring energy from an input voltage source to the resonant circuit; and
a control circuit having a burst mode for controlling the switching circuit during low energy demand conditions, in which a number of pulses are generated in intermittent bursts, and wherein the bursts are varied in a manner that reduces the amplitude of peaks in an average audio spectrum of the bursts over that of a burst having a substantially fixed pulse pattern and burst repetition rate.
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Abstract
Audible noise in resonant switching power converter during low-power burst mode operation is reduced by spreading the spectrum generated by the bursts, thereby reducing the amplitude of audio spectrum peaks in the current supplied through the resonant tank from a switching circuit. The spreading can be accomplished by varying the intervals between the bursts and/or by varying a pulse pattern within the bursts. The pulse pattern within the bursts can be varied by varying the number of pulses in the bursts, the polarity of the initial pulse of the bursts, and/or the duration of pulses within the bursts either uniformly or randomly. The burst pulse pattern may also be selected in alternation from a set of pulse patterns stored in a memory and the selection may be made randomly or systematically.
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Citations
21 Claims
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1. A resonant switching power circuit, comprising:
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a resonant circuit including at least one inductance and at least one capacitance for transferring energy to an output of the resonant switching power circuit; a switching circuit coupled to the resonant circuit for transferring energy from an input voltage source to the resonant circuit; and a control circuit having a burst mode for controlling the switching circuit during low energy demand conditions, in which a number of pulses are generated in intermittent bursts, and wherein the bursts are varied in a manner that reduces the amplitude of peaks in an average audio spectrum of the bursts over that of a burst having a substantially fixed pulse pattern and burst repetition rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of low power operation in a resonant switching power circuit, the method comprising:
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transferring energy to an output of the resonant switching power circuit from a resonant tank circuit; transferring energy from an input voltage source to the resonant circuit by operating a switching circuit; and operating the switching circuit in a burst mode, in which a number of pulses are generated in bursts to provide the energy to the output of the resonant switching power circuit intermittently when energy demand at the output of the resonant switching power circuit is low, and wherein the bursts are varied in a manner that reduces the amplitude of peaks in an average audio spectrum of the bursts over that of a burst having a substantially fixed pulse pattern and burst repetition rate. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An integrated circuit controller, integrated on a single die, for a controlling a resonant switching power converter, wherein the integrated circuit controller provides control signals to a switching circuit having a low-power burst mode, in which a number of pulses are generated in bursts when energy demand at an output of the resonant switching power converter is low, and wherein the bursts are varied in a manner that reduces the amplitude of peaks in an average audio spectrum of the bursts over that of a burst having a substantially fixed pulse pattern and burst repetition rate.
Specification