Circuits and methods for driving light sources
First Claim
1. A driving circuit, comprising:
- a first inductor coupled in series with a light emitting diode (LED) light source and for providing power to said LED light source;
a controller operable for controlling a switch coupled to said first inductor, thereby controlling a current flowing through said first inductor;
a current sensor coupled to said first inductor and operable for providing a first signal indicative of said current flowing through said first inductor, regardless of whether said switch is on or off, wherein said switch is controlled according to said first signal;
a second inductor magnetically and electrically coupled to said first inductor and operable for sensing an electrical condition of said first inductor, wherein said first inductor and said second inductor are electrically coupled to a common node between said switch and said first inductor, wherein said common node provides a reference ground for said controller, and wherein said reference ground is different from the ground of said driving circuit;
a filter coupled to said current sensor and operable for providing a second signal indicative of an average current flowing through said first inductor; and
an error amplifier operable for generating an error signal based on said second signal and a reference signal indicative of a target current level,wherein said switch is turned off if a voltage of said first signal increases above a voltage of said error signal.
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Accused Products
Abstract
A driving circuit includes a first inductor coupled in series with a light source for providing power to the light source. A controller coupled to the first inductor can control a switch coupled to the first inductor, thereby controlling a current flowing through the first inductor. A current sensor coupled to the first inductor can provide a first signal indicative of the current flowing through the first inductor, regardless of whether the switch is on or off. The switch is controlled according to the first signal. A second inductor magnetically coupled to the first inductor is also electrically coupled to the first inductor via a common node between the switch and the first inductor for providing a reference ground for the controller. The reference ground is different from the ground of the driving circuit.
106 Citations
12 Claims
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1. A driving circuit, comprising:
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a first inductor coupled in series with a light emitting diode (LED) light source and for providing power to said LED light source; a controller operable for controlling a switch coupled to said first inductor, thereby controlling a current flowing through said first inductor; a current sensor coupled to said first inductor and operable for providing a first signal indicative of said current flowing through said first inductor, regardless of whether said switch is on or off, wherein said switch is controlled according to said first signal; a second inductor magnetically and electrically coupled to said first inductor and operable for sensing an electrical condition of said first inductor, wherein said first inductor and said second inductor are electrically coupled to a common node between said switch and said first inductor, wherein said common node provides a reference ground for said controller, and wherein said reference ground is different from the ground of said driving circuit; a filter coupled to said current sensor and operable for providing a second signal indicative of an average current flowing through said first inductor; and an error amplifier operable for generating an error signal based on said second signal and a reference signal indicative of a target current level, wherein said switch is turned off if a voltage of said first signal increases above a voltage of said error signal. - View Dependent Claims (2, 3, 4, 5)
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6. A driving circuit, comprising:
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a first inductor coupled in series with a light emitting diode (LED) light source and for providing power to said LED light source; a controller operable for controlling a switch coupled to said first inductor, thereby controlling a current flowing through said first inductor; a current sensor coupled to said first inductor and operable for providing a first signal indicative of said current flowing through said first inductor, regardless of whether said switch is on or off, wherein said switch is controlled according to said first signal; a second inductor magnetically and electrically coupled to said first inductor and operable for sensing an electrical condition of said first inductor, wherein said first inductor and said second inductor are electrically coupled to a common node between said switch and said first inductor, wherein said common node provides a reference ground for said controller, and wherein said reference ground is different from the ground of said driving circuit; a filter coupled to said current sensor and operable for providing a second signal indicative of an average current flowing through said first inductor; a signal generator operable for generating a sawtooth signal; and an error amplifier operable for generating an error signal based on said second signal and a reference signal indicative of a target current level, wherein said switch is turned off if a voltage of said sawtooth signal increases to a voltage of said error signal. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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Specification