Abstract: A power supply circuit according to an embodiment includes an driver, a control circuit, and a protection circuit. The driver includes a first transistor connected between a high-potential-side power supply and a node and a second transistor connected between a low-potential-side power supply and the node. The control circuit generates, according to an output voltage to a load connected to the node via a first low-pass filter circuit, first and second switching pulses for alternately switching the first and second transistors. The protection circuit outputs, when a voltage of the node via a second low-pass filter circuit exceeds a first reference voltage, an interruption signal for making at least the first transistor nonconductive.

Abstract: A power supply circuit according to an embodiment includes an driver, a control circuit, and a protection circuit. The driver includes a first transistor connected between a high-potential-side power supply and a node and a second transistor connected between a low-potential-side power supply and the node. The control circuit generates, according to an output voltage to a load connected to the node via a first low-pass filter circuit, first and second switching pulses for alternately switching the first and second transistors. The protection circuit outputs, when a voltage of the node via a second low-pass filter circuit exceeds a first reference voltage, an interruption signal for making at least the first transistor nonconductive.

Abstract: A semiconductor integrated circuit device is employed in a DC-DC converter that switches the voltage fed to the load depending on the PWM signal. The semiconductor integrated circuit device has an error voltage generating part, a mode setting part, an oscillation signal generating part, a pulse generating part, and a control part. The oscillation signal generating part generates an oscillation signal with a prescribed period when in the non-light-load mode, and it turns off the oscillation signal when in the light-load mode. The pulse generating part generates a pulse signal before the oscillation signal generating part generates the oscillation signal when the pulse generating part switches from the light-load to the non-light-load mode.

Abstract: A semiconductor integrated circuit device is employed in a DC-DC converter that switches the voltage fed to the load depending on the PWM signal. The semiconductor integrated circuit device has an error voltage generating part, a mode setting part, an oscillation signal generating part, a pulse generating part, and a control part. The oscillation signal generating part generates an oscillation signal with a prescribed period when in the non-light-load mode, and it turns off the oscillation signal when in the light-load mode. The pulse generating part generates a pulse signal before the oscillation signal generating part generates the oscillation signal when the pulse generating part switches from the light-load to the non-light-load mode.