Patent ID: 8736214
Filing Date: 2014-05-27
Classification: H02P

Abstract:
1. A motor drive circuit, comprising: an output transistor configured to supply a drive current to a drive coil of a motor configured to cause a fan to rotate so as to blow air to cool an object to be cooled; a switching control circuit configured to control switching of the output transistor so that the motor rotates in a first direction to cool the object to be cooled, or rotates in a second direction opposite to the first direction; a switching circuit the switching control circuit including the pulse width modulation circuit includes: a frequency dividing circuit configured to be inputted with a first clock signal having a 1/2 duty ratio, frequency-divide the first clock signal, and output one or more second clock signals each of which has a period the pulse width modulation circuit generates, based on the first and the second clock signals, the pulse width modulation signal whose duty ratio is increased by 1/2