Motor driver

A motor driver that drives a motor, the motor driver comprising:

• a first series switch circuit that includes a first high-side switch element and a first low-side switch element;
• a second series switch circuit that includes a second high-side switch element and a second low-side switch element, and is connected in parallel to the first series switch circuit;
• a reference pulse generation circuit that generates, in a predetermined cycle, a reference pulse signal whose pulse duration time is greater than zero;
• a current detector that outputs a current signal corresponding to a motor current that is a current flowing through the motor;
• a reference waveform generation circuit that generates a reference waveform signal corresponding to a control target value of the motor current;
• a current comparison circuit that compares the current signal with the reference waveform signal to generate a comparison signal;
• and
• a pulse width modulation (PWM) circuit that outputs a first drive signal and a second drive signal in response to receiving the reference pulse signal, the reference waveform signal, and the comparison signal,
• wherein the motor is connected between a first connection point and a second connection point, the first connection point being a point connecting the first high-side switch element and the first low-side switch element, the second connection point being a point connecting the second high-side switch element and the second low-side switch element,
• the first drive signal includes a first pulse that starts synchronously with a start of the reference pulse signal and ends at a timing which is after the pulse duration time has elapsed from a beginning of the reference pulse signal and at which an absolute value of the current signal exceeds an absolute value of the reference waveform signal,
• the second drive signal includes a second pulse that starts after the first pulse ends and lasts at least during a period until the absolute value of the current signal falls below the absolute value of the reference waveform signal, when the absolute value of the current signal exceeds the absolute value of the reference waveform signal within the pulse duration time, and
• the PWM circuit:
• outputs the first drive signal to the first series switch circuit and the second drive signal to the second series switch circuit in a first period during which the motor current flows mainly from the first connection point to the second connection point;
• and
• outputs the second drive signal to the first series switch circuit and the first drive signal to the second series switch circuit in a second period during which the motor current flows mainly from the second connection point to the first connection point.