| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a power supply device capable of generating a drive voltage by a feedback method suited to a state of a load circuit. <P>SOLUTION: This power supply unit 100 includes a boosting circuit 10, a PWM control circuit 20, a current control circuit 16, and a gain control circuit 50. The boosting circuit 10 is a general switching regulator, which boosts an input voltage Vin inputted in an input terminal 102 and outputs it to an output terminal 104. A LED 80 of a first load circuit and a second load circuit 82, connected with the power supply unit 100, are switched for use. For constant-current driving the LED80, the current control circuit 16 includes a first feedback circuit 30 and a second feedback circuit 40. The first feedback circuit 30 is used to drive only the LED80, and the second feedback circuit 40 is used to drive the second load circuit 82. Switching between these feedback circuits is performed by a selection signal Vsel inputted from a selection terminal 108. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
