High efficiency LED driver
First Claim
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1. A light emitting diode (LED) driving circuit, comprising:
- at least two LEDs coupled between first and second nodes, a first LED being coupled in a forward current path between first and second nodes and a second LED being coupled in a reverse current path between the second and first nodes, respectively;
a power supply for producing a substantially periodic waveform, the power supply being coupled to drive the first node with voltage pulses;
a capacitor with a first and a second terminal, the first terminal is coupled to the second node of the at least two LEDs, the capacitor stores charge from the power supply while the power supply is driving the first LED in the forward current path during voltage pulses; and
a discharge circuit coupled between the second terminal of the capacitor and the first node of the at least two LEDs, wherein the discharge circuit drains charge from the capacitor to drive the second LED in the reverse current path between voltage pulses.
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Abstract
A high efficiency light emitting diode (LED) driving circuit includes a first LED coupled in a forward current path between first and second nodes and a second LED being coupled in a reverse current path between the second and first nodes. A power supply is drives the first node with voltage pulses. A capacitor is coupled to the second node and stores charge while the power supply is driving the first LED in the forward current path during voltage pulses. A discharge circuit drains charge from the capacitor to drive the second LED in the reverse current path between voltage pulses.
118 Citations
20 Claims
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1. A light emitting diode (LED) driving circuit, comprising:
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at least two LEDs coupled between first and second nodes, a first LED being coupled in a forward current path between first and second nodes and a second LED being coupled in a reverse current path between the second and first nodes, respectively;
a power supply for producing a substantially periodic waveform, the power supply being coupled to drive the first node with voltage pulses;
a capacitor with a first and a second terminal, the first terminal is coupled to the second node of the at least two LEDs, the capacitor stores charge from the power supply while the power supply is driving the first LED in the forward current path during voltage pulses; and
a discharge circuit coupled between the second terminal of the capacitor and the first node of the at least two LEDs, wherein the discharge circuit drains charge from the capacitor to drive the second LED in the reverse current path between voltage pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A light emitting diode (LED) driving circuit, comprising:
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at least two LEDs coupled between first and second nodes, a first LED being coupled in a forward current path between first and second nodes and a second LED being coupled in a reverse current path between the second and first nodes, respectively, an anode of the first LED being coupled to a cathode of the second LED at the first node and a cathode of the first LED being coupled to an anode of the second LED at the second node;
a power supply for driving the first node with voltage pulses having a substantially square waveform;
a capacitor with a first and a second terminal, the first terminal is coupled to the second node of the at least two LEDs, the capacitor stores charge from the power supply while the power supply is driving the first LED in the forward current path during voltage pulses; and
a discharge circuit coupled between the second terminal of the capacitor and the first node of the at least two LEDs, wherein the discharge circuit drains charge from the capacitor to drive the second LED in the reverse current path between voltage pulses, the stored charge of the capacitor boosts the voltage available to the second LED over a voltage available from the voltage pulses of the power supply. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A light emitting diode (LED) driving circuit, comprising:
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at least two LEDs coupled between first and second nodes, a first LED being coupled in a forward current path between first and second nodes and a second LED being coupled in a reverse current path between the second and first nodes, respectively, an anode of the first LED being coupled to a cathode of the second LED at the first node and a cathode of the first LED being coupled to an anode of the second LED at the second node;
a power supply for driving the first node with voltage pulses having a substantially square waveform;
a capacitor with a first and a second terminal, the first terminal is coupled to the second node of the at least two LEDs, the capacitor stores charge from the power supply while the power supply is driving the first LED in the forward current path during voltage pulses; and
a discharge circuit coupled between the second terminal of the capacitor and the first node of the at least two LEDs, wherein the discharge circuit drains charge from the capacitor to drive the second LED in the reverse current path between voltage pulses, the stored charge of the capacitor boosts the voltage available to the second LED over a voltage available from the voltage pulses of the power supply, the second LED requires a higher drive voltage than the first LED such that the boosted voltage available during the discharge of the capacitor equalizes photonic output between the LEDs.
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Specification