LED power supply with options for dimming

• US 20080018261A1
• Filed: 04/30/2007
• Published: 01/24/2008
• Est. Priority Date: 05/01/2006
• Status: Abandoned Application

• Current Assignee: Mark Kastner
• Original Assignee: Mark Kastner
• Inventors: Kastner, Mark
• Application Number:
  US11/796,940
• Publication Number:
  US 20080018261A1
• Time in Patent Office: Days
• US Class Current: 315/192
• CPC Class Codes: F21V 23/00 Arrangement of electric circuit elements in or on lighting devices characterised by cooling arrangements F21V29/508
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines

Abstract

A LED driver circuit is disclosed that has the ability to drive a single series string of power LEDs. The LED driver circuit uses a single stage power converter to convert from a universal AC input to a regulated DC current. This single stage power converter current is controlled by a power factor correction unit. Furthermore, the LED driver circuit contains a galvanic isolation barrier that isolates an input, or primary, section from an output, or secondary, section. The LED driver circuit can also include a dimming function, a red, green, blue output function, and a control signal that indicates the LED current and is sent from the secondary to the primary side of the galvanic barrier.

Claims

1. A LED string driver circuit consisting of:

A. A universal AC input;

B. A single stage power converter that converts power provided by the universal AC input to regulated DC current in the LED string;

C. A LED light source directly connected to the single stage power converter;

D. A power factor correction unit that controls current provided by the single stage power converter;

E. A galvanic isolation barrier;

F. An input section directly connected to the AC input; and

G. An output section that is directly connected to and powers the LED light source and is galvanically isolated from the input section by a galvanic isolation barrier.

2. The LED string driver circuit of claim 1, where said LED light source further consists of a plurality of LEDs.

3. The LED string driver circuit of claim 1, where said single stage power converter contains a Silicon Carbide rectifier.

4. The LED string driver circuit of claim 1, where said LED light source emits a constant color of light throughout the LED'"'"'s dimming range.

5. The LED string driver circuit of claim 1, where said output device includes an open secondary circuit detection function that keeps the primary voltage from appearing at this output of the device when no load is applied.

6. The LED string driver circuit of claim 1, further comprising a dimming function that is accomplished by a linear change in regulated LED current, and can be accomplished with pulse width modulation of the LED current.

7. The LED string driver circuit of claim 6, where said dimming function is controlled with a separate dimming circuit, and remotely located from the LED driver circuit.

8. The LED string driver circuit of claim 6, where said dimming function uses a dimming signal to control multiple LED driver circuits, and is optically coupled to the LED driver circuit.

9. The LED string driver circuit of claim 1, further comprising a red, green, blue output function.

10. The LED string driver circuit of claim 9, where said red, green, blue output function is used to implement a color change.

11. The LED string driver circuit of claim 1, where said galvanic isolation barrier allows for power transfer via a multiple-winding inductor.

12. The LED string driver of claim 11, where said multiple-winding inductor is provided with one or more auxiliary windings on the primary and/or secondary of the galvanic barrier.

13. The LED string driver circuit of claim 1, further comprising a control signal indicating the LED current is sent from the secondary to the primary side of the galvanic barrier.

14. The LED string driver circuit of claim 13, where said control signal can be sent across the galvanic barrier with an optical isolator.

15. The LED string driver circuit of claim 1, further comprising a power factor correction stage to correct the power factor of the power drawn from the AC input.

16. The LED string driver circuit of claim 15, where said power factor correction uses a simplified continuous-conduction-mode technique that does not require direct line voltage sensing.

17. The LED string driver circuit of claim 1, further comprising a soft-start feature to ramp the LED current from zero up to the desired value.

18. The LED string driver circuit of claim 1, further comprising a secondary over-voltage detection feature.

19. The LED string driver circuit of claim 1, further comprising multiple strings of LEDs in parallel where the current in each string of LEDs can be independently regulated.

20. The LED string driver circuit of claim 1, further comprising a separate secondary-side voltage sensing circuit that monitors bulk capacitor voltage and can send a “

shutdown”

signal to the primary side controller in the event that the bulk capacitor voltage exceeds a pre-established threshold or an output open circuit is detected.