Current detection circuit, integrated circuit, and power supply circuit

A current detection circuit for a power supply circuit configured to generate an output voltage from an input voltage thereof, the power supply circuit including

• an inductor configured to receive the input voltage,
• a transistor configured to control an inductor current flowing through the inductor, and
• a diode coupled to a first node, which is a node at which the inductor and the transistor are coupled,
• the current detection circuit being configured to detect the inductor current, the current detection circuit comprising:
• a first capacitor coupled to the first node;
• a second capacitor provided between the first capacitor and a ground, the second capacitor being coupled in series with the first capacitor;
• and
• a setting circuit configured to set a direct-current (DC) level of a voltage at a second node, which is a node at which the first capacitor and the second capacitor are coupled, wherein
• the setting circuit is a clamp circuit configured to clamp the voltage at the second node to a first level, when the transistor is off.

A power supply circuit configured to generate an output voltage from an input voltage thereof, the power supply circuit comprising:

• an inductor configured to receive the input voltage;
• a transistor configured to control an inductor current flowing through the inductor;
• a diode coupled to a first node, which is a node at which the inductor and the transistor are coupled;
• a current detection circuit configured to detect the inductor current;
• and
• an integrated circuit configured to switch the transistor, based on a detection voltage outputted from the current detection circuit, wherein
• the current detection circuit includes
• a first capacitor coupled to the first node, and
• a second capacitor provided between the first capacitor and a ground, the second capacitor being coupled in series with the first capacitor at a second node,
• a setting circuit, including a resistor, configured to set a direct-current (DC) level of a voltage at the second node, the second capacitor and the resistor forming a RC parallel circuit, which has a time constant longer than a switching period of the transistor, the current detection circuit being configured to output, as the detection voltage, the voltage at the second node;
• and
• the integrated circuit includes
• a terminal configured to receive the voltage at the second node,
• a comparator circuit configured to compare the received voltage at the terminal with a reference voltage, and
• a driver circuit configured to
• turn on the transistor, based on a result of comparison of the comparator circuit, and
• turn off the transistor, based on another voltage corresponding to the output voltage.

A power supply circuit configured to generate an output voltage from an input voltage thereof, the power supply circuit comprising:

• an inductor configured to receive the input voltage;
• a transistor configured to control an inductor current flowing through the inductor;
• a diode coupled to a first node, which is a node at which the inductor and the transistor are coupled;
• a current detection circuit configured to detect the inductor current;
• and
• an integrated circuit configured to switch the transistor, based on a detection voltage outputted from the current detection circuit, wherein
• the current detection circuit includes
• a first capacitor coupled to the first node, and
• a second capacitor provided between the first capacitor and a ground, the second capacitor being coupled in series with the first capacitor,
• a setting circuit configured to set a direct-current (DC) level of a voltage at a second node, which is a node at which the first capacitor and the second capacitor are coupled, the setting circuit being a clamp circuit configured to clamp the voltage at the second node to a first level, when the transistor is off,
• the current detection circuit being configured to output, as the detection voltage, the voltage at the second node;
• and
• the integrated circuit includes
• a terminal configured to receive the voltage at the second node,
• a comparator circuit configured to compare the received voltage at the terminal with a reference voltage, and
• a driver circuit configured to
• turn on the transistor, based on a result of comparison of the comparator circuit, and
• turn off the transistor, based on another voltage corresponding to the output voltage.