Switching control circuit and control method thereof

A control method for a switching control circuit that switches a power device, which has an insulated gate, between on and off, the control method comprising:

• applying a first voltage to a gate of the power device until a first period elapses, the first period starting when the power device is switched from off to on;
• applying a second voltage that is higher than the first voltage to the gate of the power device in a second period, the second period starting after the first period has elapsed and ending when the power device is turned off;
• increasing a gate voltage, which is applied to the gate of the power device, from the first voltage to the second voltage in a transition period, the transition period starting at a start of the second period;
• not decreasing the gate voltage of the power device even if the current value of the current flowing through the power device exceeds a pre-set threshold in a first detection period, the first detection period starting from the time the power device is switched from off to on;
• decreasing the gate voltage with a first speed if a current value of a current flowing through the power device exceeds the threshold in a second detection period, the second detection period starting after the first detection period has elapsed;
• and
• decreasing the gate voltage with a second speed that is lower than the first speed if the current value of the current flowing through the power device exceeds the threshold in a third detection period, the third detection period starting after the second detection period has elapsed;
• wherein
• an end of the first detection period is later than a timing that the gate voltage of the power device reaches the first voltage, and
• an end of the second detection period is earlier than an end of the transition period.