Patent ID: 8217584

Claim:
A driving circuit for driving light emitting diodes, the driving circuit comprising: a power supply unit having an input terminal for receiving an alternating current (AC) voltage/a first direct current (DC) voltage, and an output terminal for supplying a second DC voltage and a driving current; a series of light emitting diodes comprising at least one light emitting diode, wherein the series of light emitting diodes has a first terminal coupled to the output terminal of the power supply unit for receiving the second DC voltage and the driving current, and a second terminal; a current sink coupled to the second terminal of the series of light emitting diodes, wherein the current sink has a dimming control terminal for receiving a dimming signal; and a dimming unit for adjusting a duty cycle of an original dimming signal to generate the dimming signal according to the driving current and an ideal current, wherein the dimming unit has a first input terminal coupled to the second terminal of the series of light emitting diodes for sensing the driving current, a second input terminal for receiving the original dimming signal, a third input terminal coupled to the current sink for sensing the ideal current, and an output terminal for outputting the dimming signal.