Methods and apparatus for controlling series-connected LEDs
US7781979B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 9, 2007 |
| Grant date | Aug 24, 2010 |
| Priority date | — |
| Expiry date | Feb 17, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B45/20
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Methods and apparatus for controlling series-connected LEDs. Two or more LEDs are connected in series between a first node and a second node, wherein a series current flows between the nodes when an operating voltage is applied across the nodes. One or more controllable current paths are connected in parallel with at least a first LED for at least partially diverting the series current around at least the first LED. A controller monitors at least one parameter representative of the operating voltage, determines a maximum number of the series-connected LEDs that can be energized by the operating voltage, and controls the controllable current path(s) so as to increase an amount of the series current that is diverted around at least the first LED when the maximum number is less than a total number of all of the LEDs connected in series. In one example, the foregoing may be implemented as an integrated circuit package to provide a lighting apparatus suitable for automotive applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.