# US 2013/0154488 A1 · Dimmable LED Driver with Multiple Power Sources

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- Number: US 2013/0154488 A1
- Document ID: US20130154488A1
- Status: Published application
- Kind: A1
- Application number: 13/674,072
- Filed: 2012-11-11
- Published: 2013-06-20
- Earliest claimed: 2011-11-11
- Inventors: Laurence P. Sadwick; William B. Sackett; Jared Wyckoff
- Web page: https://patentgrep.com/patent/US20130154488A1

## CPC

- H05B 45/3725: Switched mode power supply [SMPS]
- H05B 45/14: using electrical feedback from LEDs or from LED modules
- H05B 45/382: with galvanic isolation between input and output
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL

## Abstract

A dimmable LED driver with multiple power sources.

## Claims

### Claim 1

An apparatus for powering a load, comprising:
a power input;
a load output;
a switch operable to control a flow of current from the power input to the load output;
a power storage device operable to store power from the power input when the switch is closed and to release the power when the switch is open;
a pulse generator operable to open and close the switch; and
a plurality of power sources operable to supply power to the pulse generator.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the plurality of power sources are operable to automatically change from one of the plurality of power sources to another of the plurality of power sources as a primarily active power source for the pulse generator based at least in part on a voltage level at the power input.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein at least one of the plurality of power sources comprises a power source circuit operable to draw current from the power input.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein at least one of the plurality of power sources comprises a power source circuit operable to draw power from a point other than the power input.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein at least one of the plurality of power sources comprises a power source circuit operable to draw power from the power storage device.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the power storage device comprises an inductor, and wherein the power source circuit comprises a tag-along inductor coupled to the inductor.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the inductor and the tag-along inductor are coupled with a common polarity.

### Claim 8 (depends on 6)

The apparatus of claim 6, wherein the inductor and the tag-along inductor are coupled with an inverse polarity.

### Claim 9 (depends on 5)

The apparatus of claim 5, wherein the power storage device comprises a first winding of a transformer, and wherein the power source circuit comprises a second winding of the transformer.

### Claim 10 (depends on 1)

The apparatus of claim 1, further comprising a load current controller operable to control the pulse generator to adjust a current to the load output.

### Claim 11 (depends on 1)

The apparatus of claim 1, further comprising a comparator operable to control the pulse generator based at least in part on a difference between a reference current and a signal related to a load current.

### Claim 12 (depends on 11)

The apparatus of claim 11, further comprising a time constant circuit operable to influence the reference current.

### Claim 13 (depends on 11)

The apparatus of claim 11, further comprising a time constant circuit operable to influence a measurement of the load current used by the comparator.

### Claim 14 (depends on 11)

The apparatus of claim 11, further comprising a time constant circuit operable to influence an output of the comparator.

### Claim 15 (depends on 1)

The apparatus of claim 1, wherein the power storage device is connected at a higher voltage node than the switch, and wherein the load output is referenced to the power input.

### Claim 16 (depends on 1)

The apparatus of claim 1, wherein the power storage device is connected at a lower voltage node than the switch, and wherein the load output is referenced to a ground.

### Claim 17

A method of powering a load, comprising:
generating a pulse stream in a pulse generator;
controlling a switch with the pulse stream to control a flow of current from a power input to a load output;
storing power from the flow of current when the switch is closed and releasing stored power when the switch is open; and
switchably powering the pulse generator from a plurality of power sources.

### Claim 18 (depends on 17)

The method of claim 17, wherein the plurality of power sources comprises the power input and a second power source, wherein switchably powering the pulse generator from the plurality of power sources comprises powering the pulse generator from the power input when the power input is at a higher voltage than the second power source, and powering the pulse generator from the second power source when the power input is at a lower voltage than the second power source.

### Claim 19 (depends on 18)

The method of claim 18, wherein storing power comprises storing power in an inductor, and wherein the second power source comprises a tag-along inductor coupled to the inductor.

### Claim 20 (depends on 18)

The method of claim 18, wherein storing power comprises storing power in a first winding of a transformer, and wherein the second power source comprises a second winding of the transformer.