Auxiliary Power Supply Apparatus and Method
First Claim
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1. An apparatus comprising:
- a pulse-width modulation (PWM) generator configured to generate a PWM signal for controlling a power switch of a power converter;
a bias switch and a bias capacitor connected in series and coupled to a magnetic winding of the power converter; and
a comparator having a first input connected to the bias capacitor, a second input connected to a predetermined reference and an output configured to generate a signal for controlling the bias switch to allow a magnetizing current from the magnetic winding to charge the bias capacitor when a voltage across the bias capacitor is less than the predetermined reference.
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Abstract
An apparatus includes a pulse-width modulation (PWM) generator configured to generate a PWM signal for controlling a power switch of a power converter, a bias switch and a bias capacitor connected in series and coupled to a magnetic winding of the power converter and a comparator having a first input connected to the bias capacitor, a second input connected to a predetermined reference and an output configured to generate a signal for controlling the bias switch to allow a magnetizing current from the magnetic winding to charge the bias capacitor when a voltage across the bias capacitor is less than the predetermined reference.
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Citations
24 Claims
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1. An apparatus comprising:
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a pulse-width modulation (PWM) generator configured to generate a PWM signal for controlling a power switch of a power converter; a bias switch and a bias capacitor connected in series and coupled to a magnetic winding of the power converter; and a comparator having a first input connected to the bias capacitor, a second input connected to a predetermined reference and an output configured to generate a signal for controlling the bias switch to allow a magnetizing current from the magnetic winding to charge the bias capacitor when a voltage across the bias capacitor is less than the predetermined reference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method comprising:
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detecting a voltage across a bias capacitor of a power converter; comparing the voltage across the bias capacitor with a first predetermined threshold; turning on a bias switch connected in series with the bias capacitor and using a magnetizing current to charge the bias capacitor when the voltage across the bias capacitor drops below the first predetermined threshold; and turning off the bias switch after the voltage across the bias capacitor is above a second predetermined threshold greater than the first predetermined threshold. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17-20. -20. (canceled)
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21. A device comprising:
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a controller configured to generate a gate drive signal for controlling a power switch of a power converter; a sense switch and the power switch connected in series between a magnetic winding and ground; a bias switch and a bias capacitor connected in series and coupled to the magnetic winding; and a comparator having a first input connected to the bias capacitor, a second input connected to a reference and an output configured to generate a signal for controlling the bias switch to allow a magnetizing current from the magnetic winding to charge the bias capacitor when a voltage across the bias capacitor is less than the reference. - View Dependent Claims (22, 23, 24)
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Specification