| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To suppress the ripple of an output voltage, in a power circuit which gets an output voltage by boosting input power. <P>SOLUTION: The power circuit 10 has a function of converting the voltage Vin of input power into an output voltage Vout, and it includes an error amplifier 18, a PWM circuit section 20, a driver circuit section 30, a switching transistor 22, a step-up coil 24, a diode 26, and a capacitor 28, and the output voltage Vout is returned to the error amplifier 18. The drive circuit section 30 includes a first driver, which has small drive capacity and in which an output amplitude upon switching on the switching transistor is limited, and a second driver, which has large drive capacity and in which an output amplitude upon switching on the switching transistor is not limited. The output amplitude in the switching transistor is varied by limiting a period while the second driver operates, in the first operation period while the first driver operates. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
