Patent ID: 9584052
Date: 2017-02-28
CPC Classifications: H02P

Claim:
1. A spindle motor driving apparatus coupled to a first terminal, a second terminal and a third terminal of a spindle motor, comprising: a motor controller for generating plural modulation signals and plural floating phases corresponding to the plural modulation signals, wherein a floating period comes immediately after an active period of each of the plural modulation signals, wherein a first modulation signal of the plural modulation signals corresponds to a first floating phase of the plural floating phases; a driving circuit receiving the plural modulation signals, and generating a first terminal voltage signal to the first terminal, a second terminal voltage signal to the second terminal and a third terminal voltage signal to the third terminal; a demagnetization measuring circuit connected to the first terminal, wherein at the first floating phase, the demagnetization measuring circuit measures a change of the first terminal voltage signal so as to calculate a demagnetization time of the spindle motor; and if the demagnetization time is not smaller than a threshold time period, the motor controller adjusts the plural floating phases corresponding to the plural modulation signals.