| 摘要 |
A disk apparatus spindle motor control system has a control circuit including a frequency generator for generating a master clock signal of a predetermined frequency, a first frequency divider for frequency-dividing the master clock signal by 21, 22, . . . , 2N, a second frequency divider for frequency-dividing the signal frequency-divided by 2N to generate a master index signal upon each rotation of the spindle motor, a time interval detector for detecting a time interval between the master index signal and an index signal output from a magnetic disk unit and outputting a phase control signal and a select signal corresponding to the detected time interval, a data selector for selecting and outputting one of the signals frequency-divided by 21, 22, . . . , 2N in accordance with the select signal, a clock window circuit for masking the master clock signal for a time period in accordance with the phase control signal, and a third frequency divider for frequency-dividing the output from the clock window circuit and supplying the frequency-divided signal as the clock signal to the magnetic disk unit.
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