| 摘要 |
When a PWM signal generating unit ( 10 ) sets a duty D of a PWM signal based on command signals ( 10 c), the PWM signal generating unit ( 10 ) sets a phase difference phi between each of the PWM signals based on a relation formula of phi (degree)=360 (degree)xD (%)/100 (%), and generates and outputs first PWM signals ( 10 a) and second PWM signals ( 10 b) in which the duty is D (%) and the phase difference is phi (degree). The first PWM signals ( 10 a) and the second PWM signals ( 10 b) are respectively supplied to a first load driving circuit ( 21 ) and a second load driving circuit ( 22 ) to operate a first motor fan ( 3 ) and a second motor fan ( 4 ) by a PWM control, respectively.
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