| 摘要 |
PURPOSE:To carry out stable operation at a low cost without providing any protection circuit externally. CONSTITUTION:The two ends of a motor 12 are connected with power input terminals 102, 104 of an IC 100 through resistances 30, 32 so that the power is supplied at the time of driving, and the low potential sides of coils 22, 24 in relay circuits 14, 16 for changing-over of power supply when the motor is driven are connected with an up-terminal 106 and a down-terminal 108. The IC 100 is equipped with a zenor diode 66 to produce a constant voltage, a comparator 68 to emit a signal for driving the motor when the specified level is exceeded by the potential of a charge/discharge circuit consisting of a resistance 56 and a capacitor 44 in the automatic mode, another comparator 70 which emits signal when the specified value is exceeded by the motor current, and a third comparator 72 which emits output signal when the specified potential level is exceeded by the potential of the charge/discharge circuit. When the potential of this circuit is over the specified level and also the motor current is over its specified value, the potential of the charge/discharge circuit is sunk and its time constant is changed. |
