| 摘要 |
PROBLEM TO BE SOLVED: To perform PLL correction automatically even if the load fluctuates during operation without requiring any time for manually regulating the PLL by regulating the D/A set data for altering the duty of PLL pulse thereby shifting the PLL control range. SOLUTION: In the automatic PLL regulation process, a D/A set data for altering the duty of PLL pulse is adjusted depending on the frequency difference and phase difference delivered from a PLL control section 30 thus shifting the PLL control range. In the rough regulation process, the r.p.m. of a DC motor is detected based on the FB+, FB- pulses corresponding to frequency signal and the D/A set data is adjusted such that the r.p.m. comes within the PLL control range. In a fine adjusting process, the D/A set data is adjusted such that the control can be carried out in the center of PLL control based on the phase difference between a speed clock MMTCLK corresponding to a reference signal and the FB+, FB- pulses corresponding to frequency signal. |
