Negative current sensing method for multi-channel LED driver
First Claim
1. A multi-channel power supply comprising:
- first and second power converters configured to drive respective first and second lighting sources, each of the first and second power converters respectively comprisinga first stage configured to provide current through a primary winding of an isolation transformer;
a second stage havingan energy storage device coupled in parallel with a secondary winding of the isolation transformer,a current sensing resistor coupled on a first end to the secondary winding and on a second end to a circuit ground for the second stage, anda filtering circuit coupled on a first end to a node between the secondary winding and the current sensing resistor, and on a second end to the circuit ground; and
a feedback circuit coupled between the first stage and the filtering circuit, and configured to deliver a control signal to the first stage corresponding to a current through the secondary winding.
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Accused Products
Abstract
A multi-channel LED driver is provided with a negative current sensing method for inherent output short circuit protection, as well as protection from output misconnection. A plurality of power converters are configured to drive respective LED arrays, each power converter respectively comprising a first stage configured to provide current through a primary winding of an isolation transformer. A second stage has a capacitor coupled in parallel with a secondary winding of the isolation transformer, a current sensing resistor coupled between the secondary winding and a circuit ground for the second stage. A filtering circuit is coupled on a first end to a node between the secondary winding and the current sensing resistor, and on a second end to the circuit ground. A feedback circuit is coupled between the first stage and the filtering circuit, and configured to deliver a control signal corresponding to current through the secondary winding.
13 Citations
20 Claims
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1. A multi-channel power supply comprising:
first and second power converters configured to drive respective first and second lighting sources, each of the first and second power converters respectively comprising a first stage configured to provide current through a primary winding of an isolation transformer; a second stage having an energy storage device coupled in parallel with a secondary winding of the isolation transformer, a current sensing resistor coupled on a first end to the secondary winding and on a second end to a circuit ground for the second stage, and a filtering circuit coupled on a first end to a node between the secondary winding and the current sensing resistor, and on a second end to the circuit ground; and a feedback circuit coupled between the first stage and the filtering circuit, and configured to deliver a control signal to the first stage corresponding to a current through the secondary winding. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operation for a multi-channel LED driver comprising first and second power converters, each of the first and second power converters respectively comprising an energy storage device coupled in parallel with a secondary winding of an isolation transformer, the energy storage device having a first end and a second end with the second end being coupled to a common circuit ground for the first and second power converters, and a current sensing resistor coupled between the secondary winding and the second end of the energy storage device, the method comprising:
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coupling a first end of an LED light source to a first terminal corresponding to the first end of the capacitor in the first power converter and a second end of the LED source to a second terminal corresponding to the second end of the capacitor in the second power converter; filtering out an AC ripple across the respective current sensing resistors for the first and second power converters, wherein an average current through the current sensing resistors corresponds to a DC current through the LED light source; and controlling each of the first and second power converters to provide a current through the respective secondary windings based on the sensed average current. - View Dependent Claims (11, 12, 13)
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14. A multi-channel LED driver comprising:
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first and second power converters configured to drive respective first and second lighting sources, each of the first and second power converters respectively comprising an energy storage device coupled in parallel with a secondary winding of an isolation transformer, the energy storage device having a first end and a second end with the second end being coupled to a common circuit ground for the first and second power converters, a current sensing resistor coupled between the secondary winding and the second end of the energy storage device, wherein a discharge path is defined between the energy storage device and the circuit ground, wherein a separate current return path is defined between the secondary winding and the circuit ground through the current sensing resistor, and a controller configured to provide a current through the respective secondary windings based on a sensed average current through the secondary winding. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification