Abstract: The driving circuit comprises a current control signal generator means and a current switching circuit. The current control signal generator means comprises a current mode switching circuit and a current mode switching time setting means that counts reference clock pulses and outputs a counter signal until the number of pulses counted reaches a predetermined value. The current mode switching circuit chooses a three-phase current mode or a two-phase current mode according to the counter signal being transmitted or not and transmits the current mode chosen to the current switching circuit as current control signals.

Abstract: The stepping motor controller comprising an excitation signal generator, a switching circuit, a PWM constant current control circuit and a current sensor further comprises a motor detector circuit that transmits a control signal for generating a constant current for a predetermined time for detecting the motor, a constant current generator that receives the control signal and generates the constant current to be supplied to the winding, a reference voltage generator that generates a reference voltage, a voltage comparator circuit that compares the reference voltage with a voltage drop at the winding, and a current value setting signal generator circuit that transforms an output of the voltage comparator circuit into a current value setting signal for the PWM constant current control circuit. An output of the current value setting signal generator circuit is connected to a current value setting terminal of the PWM constant current control circuit.

Abstract: The stepping motor controller comprising an excitation signal generator, a switching circuit, a PWM constant current control circuit and a current sensor further comprises a motor detector circuit that transmits a control signal for generating a constant current for a predetermined time for detecting the motor, a constant current generator that receives the control signal and generates the constant current to be supplied to the winding, a reference voltage generator that generates a reference voltage, a voltage comparator circuit that compares the reference voltage with a voltage drop at the winding, and a current value setting signal generator circuit that transforms an output of the voltage comparator circuit into a current value setting signal for the PWM constant current control circuit. An output of the current value setting signal generator circuit is connected to a current value setting terminal of the PWM constant current control circuit.

Abstract: A driving circuit of a stepping motor comprises an excitation control circuit connected to windings of a stepping motor, a driver circuit consisting of power switching transistors at a positive terminal side of a power source and of power switching transistors at a negative terminal side of the power source for controlling the excitation control circuit, a Zener diode inserted between the power source and a power input terminal of the driver circuit, and Zener diodes inserted between output terminals of the driver circuit and control signal input terminals of the power switching transistors at the positive terminal side of the power source, respectively. The Zener voltage of the Zener diode for the power switching transistor is determined to a value not less than a voltage difference between the voltage of the power source and the maximum rated voltage of the driver circuit.