Patent ID: 7265681

Claim:
A light emitted diode (LED) driving apparatus, comprising: a DC-to-DC converter, having a feedback terminal and an output terminal, wherein the DC-to-DC converter receives a feedback voltage at the feedback terminal and outputs a direct-current voltage at the output terminal; a first LED series, having a first terminal and a second terminal, wherein the first LED series receives the direct-current voltage at the first terminal and generates a first potential at the second terminal; a second LED series, having a third terminal and a fourth terminal, wherein the second LED series receives the direct-current voltage at the third terminal and generates a second potential at the fourth terminal; a first constant-current circuit, connected to the first LED series in series at the second terminal, wherein the first constant-current circuit outputs a first current for driving the first LED series according to a first control signal; a second constant-current circuit, connected to the second LED series in series at the fourth terminal, wherein the second constant-current circuit outputs a second current for driving the second LED series according to a second control signal; and a feedback circuit, for selecting the lower one of the first potential and the second potential as the feedback voltage, the feedback circuit comprising: a first diode, having a positive end electrically coupled to the feedback terminal and a negative end electrically coupled to the second terminal; a second diode, having a positive end electrically coupled to the feedback terminal and a negative end electrically coupled to the fourth terminal; and a resistance, having one end electrically coupled to the feedback terminal and the other end for receiving a reference voltage.