Motor driver device and semiconductor device

1. A motor driver device for driving a motor with a full-bridge circuit, the full-bridge circuit including a first half-bridge circuit including a first high-side transistor and a first low-side transistor directly connected to each other and a second half-bridge circuit including a second high-side transistor and a second low-side transistor directly connected to each other, the motor driver device comprising:

a switching driver configured to perform switching driving in which a switching voltage is supplied from the full-bridge circuit to the motor;

a linear driver configured to perform linear driving in which a continuous linear voltage is supplied from the full-bridge circuit to the motor; and

a control circuit configured to set a driving mode of the motor to a switching driving mode in which the switching driving is performed or a linear driving mode in which the linear driving is performed,

wherein in a current situation where a motor current flows from the first half-bridge circuit to the second half-bridge circuit through the motor, a current path through which the motor current flows by the switching driving is switched between a plurality of paths,

wherein the plurality of paths include:

a first path including a path from the first high-side transistor to the second low-side transistor via the motor;

a second path including a path from the first high-side transistor to the second high-side transistor via the motor; and

a third path including a path from the first low-side transistor to the second low-side transistor via the motor,

wherein the motor driver device further includes a detection circuit configured to detect a transition of the current path from the second path to the first path, and a discharging circuit configured to individually discharge gate charges of respective transistors constituting the full-bridge circuit,

wherein the control circuit is configured to perform the switching, in response to a detection of the transition by the detection circuit, when switching the driving mode of the motor from the switching driving mode to the linear driving mode in the current situation, in which a gate charge of the first high-side transistor and a gate charge of the second low-side transistor supplied to a gate of the first high-side transistor and a gate of the second low-side transistor by the switching driver are discharged using the discharging circuit so that the current path is one path,

wherein each of the first half-bridge circuit and the second half-bridge circuit is disposed between a predetermined power supply voltage part and a predetermined reference potential part,

wherein a connection node between the first high-side transistor and the first low-side transistor is connected to a first output terminal, a connection node between the second high-side transistor and the second low-side transistor is connected to a second output terminal, and the motor is connected between the first output terminal and the second output terminal, and

wherein the discharging circuit includes:

a first high-side discharging circuit inserted between the gate of the first high-side transistor and the first output terminal;

a first low-side discharging circuit inserted between a gate of the first low-side transistor and the reference potential part;

a second high-side discharging circuit inserted between a gate of the second high-side transistor and the second output terminal; and

a second low-side discharging circuit inserted between the gate of the second low-side transistor and the reference potential part.

2. The device of claim 1 , wherein when switching the driving mode of the motor from the switching driving mode to the linear driving mode in the current situation, the control circuit is configured to discharge the gate charge of the first high-side transistor and the gate charge of the second low-side transistor, in response to the detection of the transition by the detection circuit, through the first high-side discharging circuit and the second low-side discharging circuit.

3. The device of claim 2 , wherein each of the first high-side discharging circuit, the first low-side discharging circuit, the second high-side discharging circuit, and the second low-side discharging circuit includes a series circuit of a switch and a rectifying element, and

wherein when switching the driving mode of the motor from the switching driving mode to the linear driving mode in the current situation, the control circuit is configured to turn on the switch of each of the first high-side discharging circuit and the second low-side discharging circuit only for a predetermined time, in response to the detection of the transition by the detection circuit, so that the gate charge of the first high-side transistor and the gate charge of the second low-side transistor are discharged through the corresponding rectifying element.

4. The device of claim 3 , wherein in each of the first high-side discharging circuit, the first low-side discharging circuit, the second high-side discharging circuit, and the second low-side discharging circuit, the rectifying element is configured as a diode-connected discharging transistor.

5. The device of claim 1 , wherein a voice coil motor configured to move a magnetic head of a magnetic disk device in a radial direction of a magnetic disk is driven as the motor.

6. A semiconductor device forming the motor driver device of claim 1 ,

wherein the motor driver device is formed using an integrated circuit.

7. A motor driver device for driving a motor with a full-bridge circuit, the full-bridge circuit including a first half-bridge circuit including a first high-side transistor and a first low-side transistor directly connected to each other and a second half-bridge circuit including a second high-side transistor and a second low-side transistor directly connected to each other, the motor driver device comprising:

a switching driver configured to perform switching driving in which a switching voltage is supplied from the full-bridge circuit to the motor;

a linear driver configured to perform linear driving in which a continuous linear voltage is supplied from the full-bridge circuit to the motor; and

a control circuit configured to set a driving mode of the motor to a switching driving mode in which the switching driving is performed or a linear driving mode in which the linear driving is performed,

wherein in a current situation where a motor current flows from the first half-bridge circuit to the second half-bridge circuit through the motor, a current path through which the motor current flows by the switching driving is switched between a plurality of paths,

wherein the plurality of paths include:

a first path including a path from the first high-side transistor to the second low-side transistor via the motor;

a second path including a path from the first high-side transistor to the second high-side transistor via the motor; and

a third path including a path from the first low-side transistor to the second low-side transistor via the motor,

wherein the motor driver device further includes a detection circuit configured to detect a transition of the current path from the second path to the first path, and a discharging circuit configured to individually discharge gate charges of respective transistors constituting the full-bridge circuit,

wherein the control circuit is configured to perform the switching, in response to a detection of the transition by the detection circuit, when switching the driving mode of the motor from the switching driving mode to the linear driving mode in the current situation, in which a gate charge of the first high-side transistor and a gate charge of the second low-side transistor supplied to a gate of the first high-side transistor and a gate of the second low-side transistor by the switching driver are discharged using the discharging circuit so that the current path is one path,

wherein the control circuit is configured to receive input of predetermined information and set the driving mode of the motor to the switching driving mode when the predetermined information indicates first information or set the driving mode of the motor to the linear driving mode when the predetermined information indicates second information, and

wherein when there is a change from the first information to the second information in the predetermined information when the switching driving is performed, the control circuit is configured to wait for switching to the linear driving mode until the transition is detected by the detection circuit, and switch the driving mode of the motor from the switching driving mode to the linear driving mode in response to the detection of the transition.

8. The device of claim 7 , further comprising:

a feedback control signal generation circuit configured to generate a feedback control signal based on a current command signal that specifies a magnitude and a direction of the motor current and a detection signal of the motor current,

wherein the switching driver is configured to supply the switching voltage based on the feedback control signal to the motor in the switching driving,

wherein the linear driver is configured to supply the continuous linear voltage based on the feedback control signal to the motor in the linear driving, and

wherein the control circuit is configured to receive the current command signal as the predetermined information.

9. The device of claim 8 , wherein the control circuit is configured to:

set the driving mode of the motor to the switching driving mode when the magnitude of the motor current specified by the current command signal is larger than a predetermined value; and

set the driving mode of the motor to the linear driving mode when the magnitude of the motor current specified by the current command signal is smaller than the predetermined value.

10. A motor driver device for driving a motor with a full-bridge circuit, the full-bridge circuit including a first half-bridge circuit including a first high-side transistor and a first low-side transistor directly connected to each other and a second half-bridge circuit including a second high-side transistor and a second low-side transistor directly connected to each other, the motor driver device comprising:

a switching driver configured to perform switching driving in which a switching voltage is supplied from the full-bridge circuit to the motor;

a linear driver configured to perform linear driving in which a continuous linear voltage is supplied from the full-bridge circuit to the motor; and

a control circuit configured to set a driving mode of the motor to a switching driving mode in which the switching driving is performed or a linear driving mode in which the linear driving is performed,

wherein in a current situation where a motor current flows from the first half-bridge circuit to the second half-bridge circuit through the motor, a current path through which the motor current flows by the switching driving is switched between a plurality of paths,

wherein the plurality of paths include:

a first path including a path from the first high-side transistor to the second low-side transistor via the motor;

a second path including a path from the first high-side transistor to the second high-side transistor via the motor; and

a third path including a path from the first low-side transistor to the second low-side transistor via the motor,

wherein the motor driver device further includes a detection circuit configured to detect a transition of the current path from the second path to the first path, and a discharging circuit configured to individually discharge gate charges of respective transistors constituting the full-bridge circuit,

wherein the control circuit is configured to perform the switching, in response to a detection of the transition by the detection circuit, when switching the driving mode of the motor from the switching driving mode to the linear driving mode in the current situation, in which a gate charge of the first high-side transistor and a gate charge of the second low-side transistor supplied to a gate of the first high-side transistor and a gate of the second low-side transistor by the switching driver are discharged using the discharging circuit so that the current path is one path, and

wherein the detection circuit is configured to detect whether or not the transition of the current path from the second path to the first path has occurred based on a voltage at a connection node between the second high-side transistor and the second low-side transistor in a process of the transition of the current path from the second path to the first path.