Abstract: A control circuit for a DC-DC converter includes a controller configured to control, based on a feedback voltage, a first switch provided between an inductor and a reference potential and a second switch provided between a coupling node of the first switch and the inductor and an output terminal, a third switch provided between the second switch and the output terminal and turned off when an overcurrent flows in a coupling path between the second switch and the output terminal, and a selector configured to select a voltage of a first position which is located on a side of the second switch in the coupling path as the feedback voltage when the third switch is turned off, or a voltage of a second position which is located on a side of the output terminal in the coupling path as the feedback voltage when the third switch is turned on.

Abstract: To provide a control circuit and control method of a step-up/step-down type DC-DC converter capable of realizing high efficiency. In a state (1), a terminal Tx of a choke coil L1 is connected to an input terminal Tin, and a terminal Ty is connected to a reference potential. In a state (2), the terminal Tx is connected to the reference potential, and the terminal Ty is connected to an output terminal Tout. In the state (3), the terminal Tx is connected to the input terminal Tin, and the terminal Ty is connected to the output terminal Tout. A first period operation TO1 is constituted by the states (1) and (2), and a second period operation TO2 is constituted by the states (1) and (3). A second period T2, in which the second period operation TO2 is performed, is a value n times as long as a first period T1, in which the first period operation TO1 is performed. In the second period operation TO2, the state (1) is switched to the state (3) so that an increasing slope of an inductor current IL is reduced.

Abstract: A control circuit for a DC-DC converter includes a controller configured to control, based on a feedback voltage, a first switch provided between an inductor and a reference potential and a second switch provided between a coupling node of the first switch and the inductor and an output terminal, a third switch provided between the second switch and the output terminal and turned off when an overcurrent flows in a coupling path between the second switch and the output terminal, and a selector configured to select a voltage of a first position which is located on a side of the second switch in the coupling path as the feedback voltage when the third switch is turned off, or a voltage of a second position which is located on a side of the output terminal in the coupling path as the feedback voltage when the third switch is turned on.

Abstract: The invention includes a flip-flop circuit that controls a main switching element of a DC-DC converter by switching and an oscillation circuit that is connected to a set terminal of the flip-flop circuit and outputs an oscillation signal that gradually increases and decreases in oscillation frequency in accordance with an increase and decrease in output voltage value of the DC-DC converter when the DC-DC converter is in a transition state between a stop state and a steady operation state. In a process that the output voltage gradually rises and gradually falls, the oscillation frequency of the oscillation signal gradually rises and gradually falls, a time interval at which the main switching element is set into a conductive state is extended. No excess electric power is supplied to the output voltage, and the output voltage can be made to have a smooth ramp waveform.

Abstract: The invention includes a flip-flop circuit that controls a main switching element of a DC-DC converter by switching and an oscillation circuit that is connected to a set terminal of the flip-flop circuit and outputs an oscillation signal that gradually increases and decreases in oscillation frequency in accordance with an increase and decrease in output voltage value of the DC-DC converter when the DC-DC converter is in a transition state between a stop state and a steady operation state. In a process that the output voltage gradually rises and gradually falls, the oscillation frequency of the oscillation signal gradually rises and gradually falls, a time interval at which the main switching element is set into a conductive state is extended. No excess electric power is supplied to the output voltage, and the output voltage can be made to have a smooth ramp waveform.

Abstract: A control circuit of a DC—DC converter including a switch circuit, which outputs a step-down control signal or a step-up control signal in response to a switching signal, and a switching signal generation circuit, which is connected to the switch circuit to generate the switching signal using a duty setting signal. The switching signal generation circuit decreases the number of external terminals in a semiconductor device having the control circuit.

Abstract: A control circuit of a DC-DC converter including a switch circuit, which outputs a step-down control signal or a step-up control signal in response to a switching signal, and a switching signal generation circuit, which is connected to the switch circuit to generate the switching signal using a duty setting signal. The switching signal generation circuit decreases the number of external terminals in a semiconductor device having the control circuit.

Abstract: A switch circuit has an input terminal and an output terminal and when turned on, provides a voltage at its input terminal to its output terminal. A transistor is connected between the input and output terminals. A gate drive circuit is connected to the gate of the transistor and provides a gate drive signal to the gate. The gate drive circuit, in response to a first control signal, causes the gate drive signal to have one of a first voltage derived from an input voltage at the input terminal and a low potential voltage. A back gate drive circuit is connected to a back gate of the transistor and provides a back gate drive signal to the back gate. The back gate drive signal controls a voltage applied to the back gate of the transistor depending on whether the transistor is turned on or off. The switch circuit may be used to selectively supply battery power to a portable electronic device.

Abstract: A DC-DC converter includes a main switching device and a synchronous switching connected in series between a power supply and a ground, and a drive control circuit for supplying a first drive signal to the main switching device and a second drive signal to the synchronous switching device to alternately activate and deactivate the main switching device and the synchronous switching device. A detection circuit is connected to the synchronous switching device for detecting a malfunction of the synchronous switching device, such as a short-circuit, and generates a detection signal when a malfunction is detected. A protection circuit is connected to the detection circuit and the drive control circuit and inhibits the first and second drive signals in response to the detection signal. The drive control circuit, the detection circuit and the protection circuit are all formed on a single semiconductor substrate.