Patent ID: 9544485
Date: 2017-01-10
CPC Classifications: G03B,H04N,H05B

Claim:
1. A lighting emitting diode (LED) illumination system that operates in a boost mode and a bypass mode, comprising: a plurality of LEDs that are coupled in series to form a LED string; a plurality of bypass elements, each coupled in parallel with a respective group of one or more of the LEDs and configured to bypass selectively the respective group of LEDs in the bypass mode; a boost converter, coupled to the plurality of LEDs, that is configured to generate a drive voltage to drive the plurality of LEDs, wherein the boost converter includes a boost controller that is configured to enable the boost mode in response to a boost enable signal; and a first current sink and a second current sink, coupled to the plurality of LEDs, that are configured to provide two drive currents to drive the LEDs in the boost mode and the bypass mode, respectively; wherein in the boost mode the boost controller is electrically coupled to control the boost converter to drive the LED string by a boosted drive voltage, and in the bypass mode the boost controller is deactivated to allow the boost converter to drive a subset of the plurality of LEDs by a regular drive voltage that is substantially lower than the boosted drive voltage.