| 摘要 |
<P>PROBLEM TO BE SOLVED: To avoid a PWM mode if necessary since PWM control may generate high frequency noise. <P>SOLUTION: An H bridge drive circuit that has two arms comprising upper transistors QP1, QP2 and lower transistors QN1, QN2 connected in series and that supplies forward and reverse currents to a coil connected to a pair of output ends at junctions of the upper and lower transistors of both arms has a PWM mode in which outputs of high impedance circuits 10-1, 10-2 turn on/off the output transistors QP1, QP2, and a constant voltage mode in which an output of an operational amplifier OP controls voltages at the output ends OUT1, OUT2, and switches between them by a changeover signal STBB. <P>COPYRIGHT: (C)2013,JPO&INPIT |
