Circuits and methods for driving light sources
First Claim
1. A controller for controlling power to a light source, said controller comprising:
- a first sensing pin operable for receiving a first signal indicating an instant current flowing through an energy storage element;
a second sensing pin operable for receiving a second signal indicating whether said instant current decreases to a predetermined current level;
a driving pin operable for providing a driving signal to a switch to control a current flowing through said light source to a target current level, wherein said driving signal is generated based on one or more signals selected from said first signal and said second signal;
an error amplifier operable for generating an error signal based on said first signal and also based on a reference signal indicating said target current level, wherein the output of said error amplifier is coupled to a capacitor, anda power pin operable for receiving a voltage to power said controller,wherein said controller determines whether said light source is in a short circuit condition according to said voltage.
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Abstract
A controller for controlling power to a light source includes a first sensing pin, a second sensing pin, and a driving pin. The first sensing pin receives a first signal indicating an instant current through an energy storage element. The second sensing pin receives a second signal indicating whether the instant current decreases to a predetermined level. The driving pin provides a driving signal to a switch to control a current through the light source to a target level. The driving signal is generated based on one or more signals selected from the first signal and the second signal. The controller further includes an error amplifier for generating an error signal based on the first signal and a reference signal indicating the target level. The output of the error amplifier is coupled to a capacitor.
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Citations
23 Claims
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1. A controller for controlling power to a light source, said controller comprising:
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a first sensing pin operable for receiving a first signal indicating an instant current flowing through an energy storage element; a second sensing pin operable for receiving a second signal indicating whether said instant current decreases to a predetermined current level; a driving pin operable for providing a driving signal to a switch to control a current flowing through said light source to a target current level, wherein said driving signal is generated based on one or more signals selected from said first signal and said second signal; an error amplifier operable for generating an error signal based on said first signal and also based on a reference signal indicating said target current level, wherein the output of said error amplifier is coupled to a capacitor, and a power pin operable for receiving a voltage to power said controller, wherein said controller determines whether said light source is in a short circuit condition according to said voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A circuit for driving a light source, said circuit comprising:
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a power converter comprising a switch and an energy storage element coupled to said light source, wherein said switch is turned on and off alternately according to a driving signal to control a current flowing through said light source to a target current level; and a controller coupled to said power converter, said controller comprising; a first sensing pin operable for receiving a first signal indicating an instant current flowing through said energy storage element; a second sensing pin operable for receiving a second signal indicating whether said instant current decreases to a predetermined current level; a driving pin operable for providing said driving signal to said switch, wherein said driving signal is generated based on one or more signals selected from said first signal and said second signal; and an error amplifier operable for generating an error signal based on said first signal and also based on a reference signal indicating said target current level, wherein the output of said error amplifier is coupled to a capacitor, wherein said power converter comprises a sensor for providing said first signal, wherein a common node between said sensor and said energy storage element provides a reference ground for said controller. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A controller for controlling power to a light source, said controller comprising:
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a first sensing pin operable for receiving a first signal indicating an average current flowing through an energy storage element; a second sensing pin operable for receiving a second signal indicating whether an instant current flowing through said energy storage element decreases to a predetermined current level; a driving pin operable for providing a driving signal to a switch to control a current flowing through said light source to a target current level, wherein said driving signal is generated based on one or more signals selected from said first signal and said second signal; an error amplifier operable for generating an error signal based on said first signal and also based on a reference signal indicating said target current level, wherein the output of said error amplifier is coupled to a capacitor; and a power pin operable for receiving a voltage to power said controller, wherein said controller determines that said light source is in a short circuit condition if said voltage decreases below a threshold when said switch is off. - View Dependent Claims (22, 23)
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Specification