| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a power supply for properly setting the drive voltage of a load circuit, and enabling more efficient operation. <P>SOLUTION: In the power supply 100 for implementing a constant-current drive of a light emitting diode 300 as the load circuit, a constant-current circuit 22 is provided on a drive path of the load circuit. A charge pump circuit 10 as a voltage generating circuit outputs a drive voltage to the light-emitting diode 300. A monitor circuit 30 monitors the voltage across the constant current circuit 22. The monitor circuit 30 includes a voltage source for generating threshold voltage for tracking fluctuations of the voltage for stably operating the constant-current circuit 22, compares the voltage across the constant-current circuit with the threshold voltage generated from the voltage source, and outputs a comparison result Vs to a control section 24. The control section 24 controls the charge pump circuit 10, based on the output from a monitor circuit 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
