| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply circuit for an LED which can improve the power factor and reduce high harmonic current by using a simple method. SOLUTION: The power supply circuit 10 for an LED includes a rectifying circuit 16 and a drive circuit 22 for feeding an LED 14. The drive circuit 22 includes a switching element 26; a current detection resistance 32, of which one end is connected to a second terminal 26b of the switching element 26 and other end is connected to a zero volt line 20; and an integration circuit 34 for outputting an integration voltage Vc, in receiving a current detection voltage Vs generated at the current detection resistance 32, and a comparison circuit 42 of a PWM circuit 36 compares the integrated voltage Vc and a reference voltage Vref, and turns on the switching element 26, by outputting a reset signal to a flip-flop 38, when the integration voltage Vc reaches the reference voltage Vref. COPYRIGHT: (C)2011,JPO&INPIT |
