LED driver having constant input current
Power consumed by an LED driver may be reduced by drawing, from an electronic transformer or dimmer, an input current that is constant over a plurality of input voltages. Power derived from the constant input current is provided to the LED driver.
1. A method for reducing power consumed by an LED driver, the method comprising:
drawing, from an electronic transformer or dimmer, an input current that is substantially constant over a plurality of input voltages;
providing the input current to power the LED driver;
monitoring an output current of the LED driver; and
lowering the constant input current when the output current exceeds a threshold.
2. The method of claim 1 , wherein the constant input current is greater than or substantially equal to a minimum hold current of one of the dimmer or the electronic transformer.
3. The method of claim 1 , wherein the constant input current is greater than or substantially equal to the greater of a minimum hold current of the dimmer or a minimum hold current of the electronic transformer.
4. The method of claim 1 , wherein a value of the constant input current is previously determined.
5. The method of claim 1 , further comprising determining a value of the constant input current.
6. The method of claim 5 , wherein determining the value of the constant input current comprises adjusting the input current until a hold current of one of the electronic transformer or the dimmer is reached.
7. The method of claim 6 , wherein the reaching of the hold current is determined by a collapse of an input power waveform.
8. A system for reducing power consumed by an LED driver, the system comprising:
a constant-current sink for drawing, from an electronic transformer or dimmer, an input current that is constant over a plurality of input voltages;
an output driver for receiving the constant input current and powering an LED therewith; and
a current sensor for determining a level of an output current provided to the LED,
wherein the constant-current sink reduces the constant input current if the current sensor detects the output current increasing past a threshold.
9. The system of claim 8 , further comprising a hold-current analyzer for determining a hold current of one of the electronic transformer or dimmer, wherein the constant input current is greater than or substantially equal to the hold current.
10. The system of claim 9 , wherein the hold-current analyzer comprises digital processing logic and a storage element.
11. The system of claim 9 , wherein the hold-current analyzer comprises an input current controller for lowering the input current until a collapse of an input power waveform is detected.
12. The system of claim 8 , further comprising a storage element for storing a predetermined value of the constant input current.
13. The system of claim 8 , wherein the output driver reduces the output current if the current sensor detects the output current increasing past a threshold.
14. The system of claim 8 , wherein the constant-current sink comprises a current source or a switched-capacitor circuit.