Excitation position is changed in accordance with an external clock. The state of a full bridge circuit including four transistors connected to a coil of a stepping motor, is controlled in accordance with the excitation position. At the time of transition from the excitation position at which coil current that flows in the coil is nonzero to the excitation position at which the coil current is zero, a switch is made to (i) the inverse state where the on or off state of each of the four transistors before the transition is inverted, and then a switch is made to (ii) the off state where all the four transistors are off.

Excitation position is changed in accordance with an external clock. The state of a full bridge circuit including four transistors connected to a coil of a stepping motor, is controlled in accordance with the excitation position. At the time of transition from the excitation position at which coil current that flows in the coil is nonzero to the excitation position at which the coil current is zero, a switch is made to (i) the inverse state where the on or off state of each of the four transistors before the transition is inverted, and then a switch is made to (ii) the off state where all the four transistors are off.

A voltage regulator includes an output transistor, an error amplifier coupled to the output transistor, a cascode transistor coupled to the output transistor in series, and a cascode bias circuit coupled to the cascode transistor and the output transistor. The output transistor is configured to generate an output signal at a first voltage. The error amplifier is configured to receive a reference signal. The cascode bias circuit is configured to bias the cascode transistor such that, in response to a drain-to-source short circuit of the output transistor, the cascode transistor generates the output signal at the first voltage.

A voltage regulator includes an output transistor, an error amplifier coupled to the output transistor, a cascode transistor coupled to the output transistor in series, and a cascode bias circuit coupled to the cascode transistor and the output transistor. The output transistor is configured to generate an output signal at a first voltage. The error amplifier is configured to receive a reference signal. The cascode bias circuit is configured to bias the cascode transistor such that, in response to a drain-to-source short circuit of the output transistor, the cascode transistor generates the output signal at the first voltage.

The present disclosure provides a motor driving device. The motor driving device includes a generating unit, an adjusting unit, a converting unit and a comparing unit. The generating unit is configured to generate a sensing current corresponding to a motor current that flows through a motor coil. The adjusting unit is configured to give the sensing current a gain corresponding to a limit value of the motor current. The converting unit is configured to perform an I/V conversion on the sensing current with the gain. The comparing unit is configured to compare a reference voltage and an output voltage from the converting unit.

The present disclosure provides a motor driving device. The motor driving device includes a generating unit, an adjusting unit, a converting unit and a comparing unit. The generating unit is configured to generate a sensing current corresponding to a motor current that flows through a motor coil. The adjusting unit is configured to give the sensing current a gain corresponding to a limit value of the motor current. The converting unit is configured to perform an I/V conversion on the sensing current with the gain. The comparing unit is configured to compare a reference voltage and an output voltage from the converting unit.

A PWM signal generation unit generates a PWM signal based on a driving voltage so that a midpoint of the longer period out of an H level period and an L level period in each PWM period matches a midpoint of the PWM period. FETs of a full bridge circuit (a driving circuit) are driven according to a PWM signal, and a driving current that corresponds to an A-phase is supplied to a stepping motor. A current detector detects a driving current flowing through an A-phase winding of the motor based on a voltage that is generated across a shunt resistor, at a fixed time point that is in each PWM period and in the H level or L level period that is at the center of the PWM period.

A PWM signal generation unit generates a PWM signal based on a driving voltage so that a midpoint of the longer period out of an H level period and an L level period in each PWM period matches a midpoint of the PWM period. FETs of a full bridge circuit (a driving circuit) are driven according to a PWM signal, and a driving current that corresponds to an A-phase is supplied to a stepping motor. A current detector detects a driving current flowing through an A-phase winding of the motor based on a voltage that is generated across a shunt resistor, at a fixed time point that is in each PWM period and in the H level or L level period that is at the center of the PWM period.

The motor control device is capable of driving control of the stepping motor with a pre-excitation that excites the stepping motor for a first time with a current lower than that during driving before starting or when starting driving the stepping motor, and a post-excitation that excites the stepping motor at a current lower than that during driving when stopping or after stopping the driving of the stepping motor for a second time, and is capable of continuing the post-excitation and the pre-excitation for a period of time shorter than the sum of the first time and the second time when the post-excitation at the previous stopping of driving of the stepping motor and the pre-excitation at the next starting of driving of the stepping motor are executed without passing through the non-excited state.

The motor control device is capable of driving control of the stepping motor with a pre-excitation that excites the stepping motor for a first time with a current lower than that during driving before starting or when starting driving the stepping motor, and a post-excitation that excites the stepping motor at a current lower than that during driving when stopping or after stopping the driving of the stepping motor for a second time, and is capable of continuing the post-excitation and the pre-excitation for a period of time shorter than the sum of the first time and the second time when the post-excitation at the previous stopping of driving of the stepping motor and the pre-excitation at the next starting of driving of the stepping motor are executed without passing through the non-excited state.