Integrated circuit and power supply circuit

An integrated circuit for a power supply circuit that generates an output voltage from an AC voltage, the power supply circuit having

• a rectifier circuit that rectifies the AC voltage,
• an inductor to be applied with a rectified voltage from the rectifier circuit, and
• a transistor that controls an inductor current flowing through the inductor,
• the integrated circuit performing switching of the transistor based on the output voltage generated from the AC voltage and the inductor current, the integrated circuit comprising:
• an error output circuit that receives a feedback voltage corresponding to the output voltage, and outputs an error between the feedback voltage and a reference voltage;
• a target value generating circuit that generates a target value of the inductor current based on the error;
• a first comparison circuit that compares the inductor current and a predetermined value;
• a second comparison circuit that compares the inductor current and the target value;
• a drive circuit that turns on the transistor when the inductor current reaches the predetermined value, and turns off the transistor when the inductor current reaches the target value;
• a first adjustment circuit that reduces the target value, when the AC voltage is not being input to the rectifier circuit;
• and
• a second adjustment circuit that increases the target value, when the feedback voltage has dropped to a predetermined level while the AC voltage is being input to the rectifier circuit.

An integrated circuit for a power supply circuit that generates an output voltage from an AC voltage, the power supply circuit having

• a rectifier circuit that rectifies the AC voltage,
• an inductor to be applied with a rectified voltage from the rectifier circuit, and
• a transistor that controls an inductor current flowing through the inductor,
• the integrated circuit performing switching of the transistor based on the output voltage generated from the AC voltage and the inductor current, the integrated circuit comprising:
• an error output circuit that receives a feedback voltage corresponding to the output voltage, and outputs an error between the feedback voltage and a reference voltage;
• a target value generating circuit that generates a target value of the inductor current based on the error;
• a first comparison circuit that compares the inductor current and a predetermined value;
• a second comparison circuit that compares the inductor current and the target value;
• and
• a drive circuit that turns on the transistor, when the inductor current reaches the predetermined value, and turns off the transistor, when the inductor current reaches the target value or a predetermined time period has elapsed since the transistor has been turned on.

A power supply circuit that generates an output voltage from an AC voltage, the power supply circuit comprising:

• a rectifier circuit that rectifies the AC voltage;
• an inductor to be applied with a rectified voltage from the rectifier circuit;
• a transistor that controls an inductor current flowing through the inductor;
• and
• an integrated circuit that performs switching of the transistor, based on the output voltage and the inductor current flowing through the inductor, the integrated circuit comprising:
• an error output circuit that receives a feedback voltage corresponding to the output voltage, and outputs an error between the feedback voltage and a reference voltage;
• a target value generating circuit that generates a target value of the inductor current based on the error;
• an adjustment circuit that is connected to the target value generating circuit, and adjusts the target value;
• a first comparison circuit that compares the inductor current and a predetermined value;
• a second comparison circuit that compares the inductor current and the target value;
• and
• a drive circuit that turns on the transistor when the inductor current reaches the predetermined value, and turns off the transistor when the inductor current reaches the target value.