Patent ID: 9497812
Filing Date: 2016-11-15
CPC Classification: H05B,Y02B

Claim Text:
1. A light source driving circuit for powering a first light source and a second light source by a DC (direct current) voltage, comprising: a first current regulator, coupled to said first light source, operable for controlling a first switch coupled to said first light source based on a first current reference and a first sensing signal indicating a current flowing through said first light source; a second current regulator, coupled to said second light source, operable for controlling a second switch coupled to said second light source based on a second current reference and a second sensing signal indicating a current flowing through said second light source; a controller operable for regulating said current flowing through said first light source and said current flowing through said second light source by controlling said first current regulator and said second current regulator, wherein if said DC voltage is within a first range, then said controller turns on said first light source, and if said DC voltage is within a second range, then said controller turns on said first light source and said second light source, a first current sensor operable for providing said first sensing signal, wherein said first current sensor comprises a first resistor having a first resistance; and a second current sensor operable for providing said second sensing signal, wherein said second current sensor comprises a second resistor having a second resistance, wherein said first current reference is equal to said second current reference, said first light source comprises a first number of light emitting diodes having a first forward voltage and said second light source comprises a second number of light emitting diodes having a second forward voltage, and a ratio of said first resistance to said second resistance is equal to a ratio of said first forward voltage to a sum of said first forward voltage and said second forward voltage.