Light emitting diode multiphase driver circuit and method
DC CAFCFirst Claim
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1. A method for driving light emitting diodes (LEDs) in multiphase, comprising:
- providing a string of LEDs divided into groups, said groups of LEDs being electrically connected to each other in series;
providing a power source electrically connected to the string of LEDs;
separately coupling each of the groups to a ground through separate conductive paths;
providing a phase switch in each of the separate conductive paths;
increasing an input voltage from the power source to turn on the LEDs, group by group in a sequence downstream the string.
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Abstract
A method and a circuit for driving light emitting diodes (LEDs) in multiphase are provided. A string of LEDs divided into groups connected to each other in series is provided. Each group is coupled to ground through separate conductive paths. A phase switch is provided in each conductive path. Increasing the input voltage turn on the string of LEDs, group by group in the sequence downstream the string. To reduce power dissipation, the phase switch of an upstream group is turned off when next downstream group is turned on.
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Citations
24 Claims
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1. A method for driving light emitting diodes (LEDs) in multiphase, comprising:
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providing a string of LEDs divided into groups, said groups of LEDs being electrically connected to each other in series; providing a power source electrically connected to the string of LEDs; separately coupling each of the groups to a ground through separate conductive paths; providing a phase switch in each of the separate conductive paths; increasing an input voltage from the power source to turn on the LEDs, group by group in a sequence downstream the string. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A driver circuit for driving light emitting diodes (LEDs) in multiphase, comprising:
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a string of LEDs divided into n groups, said n groups of LEDs being electrically connected to each other in series in a sequence from group 1 to group n, each group having an upstream end and a downstream end, and the downstream end of group m−
1 being electrically connected to the upstream end of group m, where m is a positive integer equal to or less than n;a power source coupled to the upstream end of group 1 to provide an input voltage; a plurality of phase switches, each of the phase switches being coupled to the downstream end of a corresponding group at one end and coupled to a ground at the other end. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. A driver circuit for driving light emitting diodes (LEDs) with over-voltage protection, comprising:
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a group of LEDs; a power source coupled to an upstream end of the group to provide an input voltage; a phase switch coupling a downstream end of the group at one end and coupled to a ground at another end, the phase switch comprising a transistor; a over voltage protection circuit coupled between a gate of the transistor of the phase switch and a downstream end of the group.
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Specification