Current split circuit for equally splitting current between parallel connected LED luminaire strings
First Claim
Patent Images
1. A lighting circuit, comprising:
- a plurality of strings of light emitting diodes connected to a power source, the plurality of strings of light emitting diodes being connected in parallel with each other; and
a current split circuit connected to the plurality of strings of light emitting diodes, the current split circuit comprising a plurality of transistors, each transistor being directly connected to the power source, including;
a reference transistor connected in series with a first of the plurality of strings of light emitting diodes, and one or more copy transistors connected to the reference transistor and in series with one of the plurality of strings of light emitting diodes, wherein the one or more copy transistors divides the current substantially equally between the plurality of strings of light emitting diodes, wherein the plurality of transistors divide the voltage output by the power source multiple times.
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Abstract
A system and method for equally splitting the current supplied to parallel connected strings of LEDs. The system and method includes a current splitting circuit such as a mirror circuit that divides the current substantially equally between two or more parallel connected strings of LEDs. The current splitting circuit ensures that illumination levels of the strings of LEDs are uniform without requiring the strings of LEDs to be binned. The current splitting circuit also allows the strings of LEDs to be dimmed in both pulse width modulation (PWM) and continuous modes.
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Citations
19 Claims
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1. A lighting circuit, comprising:
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a plurality of strings of light emitting diodes connected to a power source, the plurality of strings of light emitting diodes being connected in parallel with each other; and a current split circuit connected to the plurality of strings of light emitting diodes, the current split circuit comprising a plurality of transistors, each transistor being directly connected to the power source, including; a reference transistor connected in series with a first of the plurality of strings of light emitting diodes, and one or more copy transistors connected to the reference transistor and in series with one of the plurality of strings of light emitting diodes, wherein the one or more copy transistors divides the current substantially equally between the plurality of strings of light emitting diodes, wherein the plurality of transistors divide the voltage output by the power source multiple times. - View Dependent Claims (2, 3, 4, 5)
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6. A lighting method, comprising:
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providing a power source; providing a plurality of strings of light emitting diodes in communication with the power source, the plurality of strings of light emitting diodes being connected in parallel with each other; providing a current split circuit in communication with the plurality of strings of light emitting diodes, the current split circuit having a plurality of transistors that form a mirror circuit, each transistor being directly connected to the power source; dividing the current equally between each of the plurality of strings of light emitting diodes such that the light emitting diodes are illuminated at substantially the same level; and dividing, by the plurality of transistors, the voltage output by the power source multiple times. - View Dependent Claims (7, 8, 9)
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10. A lighting circuit comprising:
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a plurality of strings of lighting devices configured to emit light; a power source configured to supply power to the plurality of strings of lighting devices; and a current split circuit comprising; a plurality of transistors in communication with each other, and configured to control the power supplied to the plurality of strings of lighting devices, wherein the plurality of strings of lighting devices are in parallel with each other via the current split circuit, and each string of lighting devices is connected in series with only a transistor within the plurality of transistors, and a transistor of the plurality of transistors taps a current at another transistor of the plurality of transistors such that the current split circuit divides the current substantially equal between the plurality of lighting devices, wherein each transistor is directly connected to the power source, and the plurality of transistors divide the voltage output by the power source multiple times. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification