| 摘要 |
A control technique for keeping a revolution with the same or specific relationship by giving a feedback of the revolution to each fan in order to reduce "beating sound" arising due to rotational errors of each fan in using a plurality of fans on an electronic apparatus and the like, wherein the revolutions of a plurality of fans can be controlled stably and accurately in a simple circuit configuration. A control fan revolution control circuit (606 (#i)) at first controls a control fan PWM signal (615 (#i)) to be supplied to a control fan (602 (#i)) by comparing each of revolution signals (613, 614) respectively corresponding to a reference fan (601) and the control fan (602 (#i)) such that the revolutions of the fans (601) and (602 (#i)) may be substantially matched, and subsequently controls a control fan power supply signal (616 (#i)) to be supplied to the control fan (602 (#i)) to ensure matching control of the revolutions exceeding that of the PWM control. |
