| 摘要 |
PROBLEM TO BE SOLVED: To provide a motor driver which can gradually adjust noise mask time and position detection time, according to the rotational speed of a brushless motor. SOLUTION: A circuit for generating a noise mask signal for removing the counter noise from a rectangular wave signal, obtained by comparing the induced voltage of the coil of a motor with the midpoint voltage generates analogous triangular wave signals L1 and L2 which are different in frequency, according to the number of revolutions of the motor. The motor driver determines a reference current value Is=Ip/n, by dividing the amplitude Ip of the triangular signals L1 and L2, after the voltage-to-current conversion of these triangular wave signals S1 and S2 into n:1, and generates a noise mask signal, by comparing the triangular wave signals L1 and L2 with a reference current value Is. |
