| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an LED drive circuit capable of decreasing power loss in a low-light mode. <P>SOLUTION: The LED drive circuit incudes: a resistor R1 for setting the value of a constant current; a switching power supply circuit (an N-channel MOSFET1, a control circuit 2', a switching transformer T1, a diode D1, and a capacitor C2) for outputting a DC output voltage; and a constant current power supply circuit (a driver 6', a diode D2, a coil L1, and a capacitor C3) for inputting the DC output voltage and outputting the constant current to drive an LED 7. When driving the LED 7 with low-light mode by the current smaller than that of ordinary lighting mode, at least one oscillating frequency of an oscillating circuit in the switching power supply circuit and an oscillating circuit in the constant current power supply circuit is lowered than that of the ordinary lighting mode. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
