Patent ID: 9313843
Filing Date: 2016-04-12
CPC Classification: H05B

Claim Text:
1. A system comprising: a dimming controller configured to generate (i) a first dimming signal having a first dimming frequency, and (ii) a second dimming signal having a second dimming frequency; a first LED switch configured to receive the first dimming signal, and to switch on or off a first LED string in response to the first dimming signal; a second LED switch configured to receive the second dimming signal, and to switch on or off a second LED string in response to the second dimming signal, wherein the second LED string is coupled in parallel with the first LED string; and a detection circuit configured to generate a comparison signal indicating whether a first voltage drop of the first LED string is larger than a second voltage drop of the second LED string, wherein the dimming controller is further configured control the first dimming signal and the second dimming signal to