Shunting type PWM dimming circuit for individually controlling brightness of series connected LEDS operated at constant current and method therefor
US7723926B2 · kind B2 · utility
34Cited by
1References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 14, 2007 |
| Grant date | May 25, 2010 |
| Priority date | — |
| Expiry date | Dec 27, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B45/385
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A dimming circuit for driving a string of LEDs at constant current has a power converter. A control circuit is coupled to the power converter. A plurality of shunt switches is provided. An individual shut switch is coupled to each LED. Each LED can be shunted individually by the individual shunt switch. The control circuit corrects an internal DC state based on a feedback signal VO so that the output current of the power converter remains unchanged when at least one LED is shunted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.