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; and
a second series interconnection of a second LED group, a second transistor, and a second resistor, wherein;
the second series interconnection is connected to the first transistor, and the first and second LED groups are selectively activated by a variable voltage applied across the first series interconnection;
wherein the first and second transistors are depletion MOSFET transistors; and
wherein the first resistor is coupled between the source terminal and a gate terminal of the first transistor, and the first transistor transitions from a conducting state to a non-conducting state when the variable voltage exceeds a first threshold.
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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.
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Citations
12 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; and
a second series interconnection of a second LED group, a second transistor, and a second resistor, wherein;
the second series interconnection is connected to the first transistor, and the first and second LED groups are selectively activated by a variable voltage applied across the first series interconnection;wherein the first and second transistors are depletion MOSFET transistors; and wherein the first resistor is coupled between the source terminal and a gate terminal of the first transistor, and the first transistor transitions from a conducting state to a non-conducting state when the variable voltage exceeds a first threshold. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A circuit comprising:
- 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 the first LED group and the first transistor, and the first and second LED groups are selectively activated by a variable voltage applied across the first series interconnection;wherein the first and second transistors are depletion MOSFET transistors; and wherein the first resistor is coupled between the source terminal and a gate terminal of the first transistor, and the first transistor transitions from a conducting state to a non-conducting state when the variable voltage exceeds a first threshold. - View Dependent Claims (8, 9, 10, 11, 12)
- a first series interconnection of a first light-emitting diode (LED) group, a first transistor, and a first resistor; and
Specification