| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an LED power supply circuit enabling a light control from zero percent without turning on/off an LED driving current. <P>SOLUTION: An LED power supply circuit includes: a converting part 8 including at least series connection of an inductor T2a and a switching element Q1 and converts DC power supply to a direct current of a desired magnitude by storing/discharging a magnetic field energy of the inductor T2a coordinating with on-off drive of the switching element Q1; and a control circuit 14 for controlling a drive of the switching element Q1 on the basis of a designated dimming degree. When the dimming degree is a reference value or higher, the control circuit 14 defines an ON width of the switching element Q1 according to the dimming degree to turns off, and turns on at the timing when current flowing in the inductor T2a becomes nearly zero. When the dimming degree is a reference value or lower, the control circuit 14 defines the ON width of the switching element Q1 according to the dimming degree to turns off, and turns on with a driving period being fixed. <P>COPYRIGHT: (C)2013,JPO&INPIT |
