LED driver with high dimming compatibility without the use of bleeders
First Claim
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1. A circuit for controlling a switching converter, the circuit comprising:
- an input voltage or phase analyzer for detecting when a dimmer circuit supplying power to the switching converter changes from a conducting state to a nonconducting state or from a nonconducting state to a conducting state; and
a pulse-width-modulating generator for changing an equivalent input resistance of the switching converter to a first, higher value when the dimmer circuit is in the conducting state and to a second, lower value when the dimmer circuit is in the nonconducting state, thereby drawing a minimum current from the dimmer circuit while the dimmer circuit is in the nonconducting state,wherein the pulse-width-modulating generator changes the equivalent input resistance at a first point in time prior to a second point in time at which the state of the dimmer circuit changes.
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Abstract
A switching converter detects when a dimmer circuit supplying power to the switching converter changes from a conducting state to a nonconducting state or from a nonconducting state to a conducting state; an equivalent input resistance of the switching converter is changed to a first, higher value when the dimmer circuit is in the conducting state and to a second, lower value when the dimmer circuit is in the nonconducting state, thereby drawing a minimum current from the dimmer circuit while the dimmer circuit is in the nonconducting state.
37 Citations
13 Claims
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1. A circuit for controlling a switching converter, the circuit comprising:
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an input voltage or phase analyzer for detecting when a dimmer circuit supplying power to the switching converter changes from a conducting state to a nonconducting state or from a nonconducting state to a conducting state; and a pulse-width-modulating generator for changing an equivalent input resistance of the switching converter to a first, higher value when the dimmer circuit is in the conducting state and to a second, lower value when the dimmer circuit is in the nonconducting state, thereby drawing a minimum current from the dimmer circuit while the dimmer circuit is in the nonconducting state, wherein the pulse-width-modulating generator changes the equivalent input resistance at a first point in time prior to a second point in time at which the state of the dimmer circuit changes. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for controlling a switching converter, the method comprising:
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detecting when a dimmer circuit supplying power to the switching converter changes from a conducting state to a nonconducting state or from a nonconducting state to a conducting state; and changing an equivalent input resistance of the switching converter to a first, higher value when the dimmer circuit is in the conducting state and to a second, lower value when the dimmer circuit is in the nonconducting state, thereby drawing a minimum current from the dimmer circuit while the dimmer circuit is in the nonconducting state, wherein changing the equivalent input resistance includes changing at a first point in time prior to a second point in time at which the state of the dimmer circuit changes. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification