Gate driver circuit

A gate driver circuit for driving a high-side transistor and a low-side transistor forming a switching circuit, the gate driver circuit comprising:

• a high-side driver configured to drive the high-side transistor, a driving capability of the high-side driver being switchable in multiple stages including a first capability, a second capability lower than the first capability, and a third capability higher than the first capability;
• a low-side driver configured to drive the low-side transistor;
• a first output sensor configured to compare an output voltage of the switching circuit with a first threshold voltage, and to generate a first output detection signal that takes a first level when the output voltage is higher and takes a second level when the output voltage is lower;
• a high-side gate sensor configured to assert a high-side OFF detection signal when a gate-source voltage of the high-side transistor becomes lower than a predetermined voltage level;
• and
• a control circuit configured to switch between a high output state in which the high-side transistor is ON and the low-side transistor is OFF, a low output state in which the high-side transistor is OFF and the low-side transistor is ON, and a high impedance state in which the high-side transistor and the low-side transistor are OFF, by controlling the high-side driver and the low-side driver,
• wherein the control circuit is configured to, when the switching circuit operates in a source mode:
• (i) enter a first period when an instruction for transition from the high output state to the high impedance state occurs, and set the driving capability of the high-side driver to the first capability in the first period;
• (ii) enter a second period when the first output detection signal changes to the second level in the first period, and set the driving capability of the high-side driver to the second capability in the second period;
• and
• (iii) enter a third period when assertion of the high-side OFF detection signal occurs in the second period, and set the driving capability of the high-side driver to the third capability in the third period.