Integrated circuit and power supply circuit

A power supply circuit configured to generate a direct-current voltage from an alternating-current voltage, the power supply circuit comprising:

• an inductor to receive a rectified voltage corresponding to the alternating-current voltage;
• a power transistor configured to control an inductor current flowing through the inductor;
• and
• an integrated circuit configured to drive the power transistor,
• the integrated circuit including
• a first transistor coupled to a power supply line to receive a power supply voltage,
• a diode provided between the power supply line and a gate electrode of the first transistor, and
• a current generation circuit provided on a side of a ground with respect to the diode, the current generation circuit being configured to
• generate a current for the diode, upon turning on of the first transistor, and
• increase the current, upon the power supply voltage dropping below a first level.

A signal output circuit comprising:

• a first transistor coupled to a power supply line to receive a power supply voltage;
• a diode provided between the power supply line and a gate electrode of the first transistor;
• and
• a current generation circuit provided on a side of a ground with respect to the diode, the current generation circuit being configured to generate a current for the diode upon turning on of the first transistor, wherein
• the current generation circuit, through which the current flows upon turning on of the first transistor, has a resistance value that decreases upon the power supply voltage dropping below a first level.