Patent ID: 8773041

Claim:
A light-emitting diode (LED) device driving method, the method comprising: a) receiving an AC input voltage to obtain an absolute value of said AC input voltage; b) receiving a DC bus voltage, and generating a driving voltage and a driving current for said LED device through a power switch, wherein said DC bus voltage is obtained by rectifying said AC input voltage; c) generating a first reference voltage according to said driving current and an expected driving current of said LED device; d) comparing said absolute value of said AC input voltage against a sum of said driving voltage and said first reference voltage; e) turning off said power switch when said absolute value of said AC input voltage is greater than said sum of said driving voltage and said first reference voltage; and f) turning on said power switch to generate an output current when said absolute value of said AC input voltage is greater than said driving voltage and less than said sum of said driving voltage and said first reference voltage, wherein an average value of said output current substantially matches said expected driving current.