Load drive circuit, motor drive control device, and motor unit

A motor drive control device comprising:

• a control circuit configured to generate a drive control signal;
• a power source terminal supplied with a power source voltage;
• a power source line;
• a protection circuit including two N-channel type transistors connected in series between the power source terminal and the power source line;
• wherein each N-channel type transistor comprises a control electrode,
• an inverter circuit configured to drive a motor based on the drive control signal from the control circuit, the inverter circuit being disposed between the power source line and a ground potential;
• and
• a booster unit configured to generate a voltage exceeding the power source voltage, and apply the voltage to both the control electrodes, wherein:
• the inverter circuit includes a plurality of switching legs each including two transistors for driving connected in series between the power source line and the ground potential;
• and
• the booster unit includes a capacitor, a first rectifier element, and a second rectifier element, wherein:
• one terminal of the capacitor is connected to a connection node between one of the switching legs,
• the first rectifier element is connected between the power source terminal and the other terminal of the capacitor, and configured to flow current to the capacitor side from the power source terminal side, and
• the second rectifier element is connected between the other terminal of the capacitor and the control electrode of the two N-channel type transistors, configured to flow current to the control electrode side of the two N-channel type transistors from the capacitor side.

A motor unit comprising:

• a motor;
• and
• a motor drive control device, wherein the motor drive control device includes:
• a control circuit configured to generate a drive control signal;
• a power source terminal supplied with a power source voltage;
• a power source line;
• a protection circuit including two N-channel type transistors connected in series between the power source terminal and the power source line;
• wherein each N-channel type transistor comprises a control electrode;
• an inverter circuit configured to drive a load based on a drive control signal from the control circuit, the inverter circuit being disposed between the power source line and a ground potential;
• and
• a booster unit configured to generate a voltage exceeding the power source voltage, and apply the voltage to both the control electrodes, wherein:
• the inverter circuit includes a plurality of switching legs each including two transistors for driving connected in series between the power source line and the ground potential;
• and
• the booster unit includes a capacitor, a first rectifier element, and a second rectifier element, wherein:
• one terminal of the capacitor is connected to a connection node between one of the switching legs,
• the first rectifier element is connected between the power source terminal and the other terminal of the capacitor, and configured to flow current to the capacitor side from the power source terminal side, and
• the second rectifier element is connected between the other terminal of the capacitor and the control electrode of the two N-channel type transistors, configured to flow current to the control electrode side of the two N-channel type transistors from the capacitor side.