Driving circuitry for LED lighting with reduced total harmonic distortion
First Claim
1. A circuit comprising:
- a first series interconnection of a first light-emitting diode (LED) group, a first transistor, and a first resistor;
a second series interconnection of a second LED group, a second transistor, and a second resistor, wherein;
the second series interconnection is connected between a drain terminal and a source terminal of the first transistor, andthe first and second LED groups are selectively activated by a variable voltage applied across the first series interconnection; and
a rectifier receiving an AC driving voltage at a pair of input terminals, rectifying the received AC driving voltage, and outputting the rectified voltage as the variable voltage at a pair of output nodes,wherein;
an anode of the first LED group is coupled to one of the pair of output nodes of the rectifier;
a cathode of the first LED group is coupled to the drain terminal of the first transistor;
the source terminal of the first transistor is coupled to a first terminal of the first resistor; and
a gate terminal of the first transistor is coupled to a second terminal of the first resistor and to the other of the pair of output nodes of the rectifier.
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Accused Products
Abstract
Conditioning circuits are provided for driving two or more LED groups using a rectified AC input voltage. The conditioning circuits uses analog circuitry to gradually and selectively activate the LED groups based on an instantaneous value of the rectified input voltage. The circuit includes a first series interconnection of a first LED group, a first transistor, and a first resistor, and a second series interconnection of a second LED group, a second transistor, and a second resistor. In one example, the second series interconnection is connected between a drain terminal and a source terminal of the first transistor, while in another example, the second series interconnection is connected between an anode of the first LED group and a source terminal of the first transistor. The first and second LED groups are selectively activated by the rectified voltage applied across the first series interconnection.
121 Citations
14 Claims
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1. A circuit comprising:
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a first series interconnection of a first light-emitting diode (LED) group, a first transistor, and a first resistor; a second series interconnection of a second LED group, a second transistor, and a second resistor, wherein; the second series interconnection is connected between a drain terminal and a source terminal of the first transistor, and the first and second LED groups are selectively activated by a variable voltage applied across the first series interconnection; and a rectifier receiving an AC driving voltage at a pair of input terminals, rectifying the received AC driving voltage, and outputting the rectified voltage as the variable voltage at a pair of output nodes, wherein; an anode of the first LED group is coupled to one of the pair of output nodes of the rectifier; a cathode of the first LED group is coupled to the drain terminal of the first transistor; the source terminal of the first transistor is coupled to a first terminal of the first resistor; and a gate terminal of the first transistor is coupled to a second terminal of the first resistor and to the other of the pair of output nodes of the rectifier. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit comprising:
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a first series interconnection of a first light-emitting diode (LED) group, a first transistor, and a first resistor; and a second series interconnection of a second LED group, a second transistor, and a second resistor, wherein; the second series interconnection is connected between an anode of the first LED group and a source terminal of the first transistor, and the first and second LED groups are selectively activated by a variable voltage applied across the first series interconnection; and a rectifier receiving an AC driving voltage at a pair of input terminals, rectifying the received AC driving voltage, and outputting the rectified voltage as the variable voltage at a pair of output nodes, and wherein; the anode of the first LED group is coupled to one of the pair of output nodes of the rectifier; a cathode of the first LED group is coupled to a drain terminal of the first transistor; the source terminal of the first transistor is coupled to a first terminal of the first resistor; and a gate terminal of the first transistor is coupled to a second terminal of the first resistor and to the other of the pair of output nodes of the rectifier. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification