Startup Circuit and Power Converter Employing the Same
First Claim
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1. A startup circuit for a controller, comprising:
- a charge accumulation circuit having a resistor series-coupled to a capacitor;
a first Schmitt trigger having an input coupled to said capacitor;
a second Schmitt trigger having an input coupled to an output of said first Schmitt trigger and configured to provide a bias voltage for said controller via said capacitor when an input voltage thereto exceeds a trip voltage.
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Abstract
A startup circuit with reduced power dissipation, method of operating the same and a power converter employing the startup circuit. In one embodiment, the startup circuit for a controller includes a charge accumulation circuit having a resistor series-coupled to a capacitor and a first Schmitt trigger having an input coupled to the capacitor. The startup circuit also includes a second Schmitt trigger having an input coupled to an output of the first Schmitt trigger and configured to provide a bias voltage for the controller via the capacitor when an input voltage thereto exceeds a trip voltage.
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Citations
20 Claims
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1. A startup circuit for a controller, comprising:
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a charge accumulation circuit having a resistor series-coupled to a capacitor; a first Schmitt trigger having an input coupled to said capacitor; a second Schmitt trigger having an input coupled to an output of said first Schmitt trigger and configured to provide a bias voltage for said controller via said capacitor when an input voltage thereto exceeds a trip voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method operable with a controller, comprising:
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charging a capacitor of a charge accumulation circuit; causing a first Schmitt trigger to turn on when a voltage across said capacitor coupled to an input thereof exceeds a trip voltage; causing a second Schmitt trigger to turn on when said first Schmitt trigger is conducting; and providing a bias voltage for said controller from said capacitor when said second Schmitt trigger is conducting. - View Dependent Claims (12, 13, 14, 15)
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16. A power converter couplable to a source of electrical power, comprising:
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a power train having a power switch couplable to said source of electrical power; a controller configured to control said power switch; and a startup circuit, including; a charge accumulation circuit couplable to said source of electrical power and having a resistor series-coupled to a capacitor, a first Schmitt trigger having an input coupled to said capacitor; a second Schmitt trigger having an input coupled to an output of said first Schmitt trigger and configured to provide a bias voltage for said controller via said capacitor when an input voltage thereto exceeds a trip voltage. - View Dependent Claims (17, 18, 19, 20)
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Specification