Power supply for LEDs
DCFirst Claim
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1. A system for supplying power for LEDs comprising:
- means for sensing current to the LEDs, the current sensing means generating a sensed current signal;
means for generating a reference current signal;
means for comparing the sensed current signal to the reference current signal, the comparing means generating a feedback signal;
means for converting power responsive to the feedback signal, the power converting means supplying current to the LEDs; and
means for protecting the LEDs.
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Abstract
The power supply for LEDs of the present invention provides power to a variable number of LEDs wired in series or in parallel. The power supply uses current feedback to adjust power to the LEDs and provides protection against open circuits and circuit malfunctions. A current controller compares sensed current to a reference current and generates a feedback signal, which is processed by a power factor corrector to adjust the current flow through the transformer supplying current to the LEDs.
373 Citations
41 Claims
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1. A system for supplying power for LEDs comprising:
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means for sensing current to the LEDs, the current sensing means generating a sensed current signal;
means for generating a reference current signal;
means for comparing the sensed current signal to the reference current signal, the comparing means generating a feedback signal;
means for converting power responsive to the feedback signal, the power converting means supplying current to the LEDs; and
means for protecting the LEDs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 32, 33, 34)
a PFC responsive to the feedback signal, the PFC generating a gate drive signal;
means for regulating a transformer responsive to the gate drive signal, the transformer regulating means generating a transformer control signal; and
a flyback transformer responsive to the transformer control signal, the flyback transformer supplying current to the LEDs.
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7. The system of claim 6 wherein the transformer regulating means is selected from the group consisting of a transistor, a MOSFET, an IGBT, and a bipolar transistor.
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8. The system of claim 1 wherein the comparing means is a proportional type op-amp control circuit.
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9. The system of claim 1 further comprising means for isolating the comparing means from the power converting means.
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10. The system of claim 9 wherein the isolating means is an optocoupler.
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11. The system of claim 1 wherein the reference current signal generating means is a forward converter transformer supplying a zener diode circuit.
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32. The system of claim 1 wherein the LED protecting means comprises means for limiting voltage to the LEDs.
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33. The system of claim 32 wherein the voltage limiting means limits the sensed current signal.
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34. The system of claim 32 wherein the voltage limiting means limits the feedback signal.
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12. A method of supplying power for LEDs comprising the steps of:
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sensing current to the LEDs and generating a sensed current signal;
generating a reference current signal;
comparing the sensed current signal to the reference current signal;
generating a feedback signal based on the difference between the sensed current signal and the reference current signal;
converting power and supplying current to the LEDs in response to the feedback signal; and
protecting the LEDs. - View Dependent Claims (13, 14, 15, 16, 17, 18, 35, 36, 37)
generating a gate drive signal based on the feedback signal;
generating a transformer control signal based on the gate drive signal; and
supplying current to the LEDs based on the transformer control signal.
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18. The method of claim 12 wherein the step of comparing the sensed current signal to the reference current signal further comprises the step of comparing the sensed current signal to the reference current signal with a proportional type op-amp control circuit.
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35. The method of claim 12 wherein the step of protecting the LEDs comprises the step of limiting voltage to the LEDs.
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36. The method of claim 35 wherein the step of limiting voltage limits the sensed current signal.
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37. The method of claim 35 wherein the step of limiting voltage limits the feedback signal.
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19. A circuit for supplying power for LEDs comprising:
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a transformer, the transformer supplying current to the LEDs and being responsive to a transformer control signal;
a current sensor for sensing current to the LEDs, the current sensor generating a sensed current signal;
a current reference for generating a reference current signal;
a current controller for comparing the sensed current signal to the reference current signal, the current controller generating a feedback signal;
a PFC responsive to the feedback signal, the PFC generating a gate drive signal;
a transistor responsive to the gate drive signal, the transistor generating the transformer control signal; and
a protective circuit limiting the current to the LEDs. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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38. A circuit for supplying power for LEDs comprising:
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a transformer, the transformer supplying current to the LEDs and being responsive to a transformer control signal;
a current sensor for sensing current to the LEDs, the current sensor generating a sensed current signal;
a current reference for generating a reference current signal;
a current controller for comparing the sensed current signal to the reference current signal, the current controller generating a feedback signal;
a PFC responsive to the feedback signal, the PFC generating a gate drive signal;
a transistor responsive to the gate drive signal, the transistor generating the transformer control signal; and
a protective circuit limiting the voltage to the LEDs. - View Dependent Claims (39, 40, 41)
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Specification