Abstract: An integrated circuit for a power supply including a power transistor, the integrated circuit being configured to switch and drive the power transistor. The integrated circuit includes: a first terminal to which a first switch is coupled; a first determination circuit configured to determine, based on a voltage level at the first terminal, whether to operate the integrated circuit in a first mode or a second mode, a power consumption in the second mode being greater than a power consumption in the first mode; a first power supply voltage generation circuit configured to stop generating a first power supply voltage when the integrated circuit operates in the first mode, and generate the first power supply voltage when the integrated circuit operates in the second mode; and a driver circuit configured to receive the first power supply voltage, to switch and drive the power transistor.

Abstract: A power supply circuit of a step-down type, configured to generate an output voltage at a predetermined level from an alternating current (AC) voltage. The power supply circuit includes a rectifier circuit configured to rectify the AC voltage, a first line coupled to the rectifier circuit, a second line on a ground side, a switch coupled between the first line and the second line, and a control circuit configured to control the switch to bring a level of the output voltage to the predetermined level. The power supply circuit is free of an inductor interposed between the first line and the rectifier circuit.

Abstract: Included are a switching power supply device main body, and a frequency control circuit that controls the switching frequency of a switching element in accordance with a feedback signal in accordance with the output voltage of the switching power supply device main body. The frequency control circuit is divided into a frequency control region wherein the amount of the feedback signal is greater than a predetermined boundary value and a frequency control region wherein the amount is less, linear frequency control whereby the switching frequency of the switching element is caused to change linearly in accordance with the feedback signal is executed in the frequency control region wherein the feedback amount is less, and linear cycle control whereby the switching cycle of the switching element is caused to change linearly in accordance with the feedback signal is executed in the frequency control region wherein the feedback amount is greater.

Abstract: A power supply system of the present invention aims to achieve optimization of the efficiency and therefore includes: z (z is a natural number equal to or larger than 2) power supplies (PS-1 to PS-z) connected in parallel; and a controller (8) for the number of power supplies in operation which controls the number of power supplies in operation among the power supplies (PS-1 to PS-z).

Abstract: Included are a switching power supply device main body, and a frequency control circuit that controls the switching frequency of a switching element in accordance with a feedback signal in accordance with the output voltage of the switching power supply device main body. The frequency control circuit is divided into a frequency control region wherein the amount of the feedback signal is greater than a predetermined boundary value and a frequency control region wherein the amount is less, linear frequency control whereby the switching frequency of the switching element is caused to change linearly in accordance with the feedback signal is executed in the frequency control region wherein the feedback amount is less, and linear cycle control whereby the switching cycle of the switching element is caused to change linearly in accordance with the feedback signal is executed in the frequency control region wherein the feedback amount is greater.

Abstract: A switching power supply device that includes a feedback terminal to which a feedback signal according to a load state is input, and a comparator which compares a terminal voltage of the feedback terminal with a reference voltage and determines whether the load state is a normal load state or a light load state. The switching power supply device also includes pull-up resistors which are connected to the feedback terminal, a switch element which switches resistance values of the pull-up resistors according to the change of the load state, and a switch element which switches the resistance values of the pull-up resistors according to whether the input voltage is high or low.

Abstract: A switching regulator can include a transformer having a primary winding and a secondary winding, a switching circuit including a switching element that is connected in series to the primary winding, the series-connected circuit of the switching element and the primary winding being connected in parallel to a DC power supply and a rectifying circuit connected to the secondary winding. The switching regulator can also include a control circuit to control switching of the switching element to generate DC output voltage from the DC power supply, the DC output voltage being insulated from the DC power supply, an output voltage detecting circuit including a photo-coupler for insulated detection of the DC output voltage, the photo-coupler having a photo-transistor and a load quantity detector for detecting a state in which power consumption in the load connected to the DC output has reached a predetermined value.

Abstract: The voltage of a detection resistor connected to the drain of a low-side switching device is normally a negative voltage, but a positive voltage appears when a countercurrent occurs in an abnormal state. A current comparator monitors the voltage of the detection resistor, transmits high output to an AND circuit whole the voltage of the detection resistor is a negative voltage to maintain the output voltage of the current comparator in a low state when an output signal of a driver can be transmitted to the low-side switching device, and allows the output voltage of the current comparator in a low state when the voltage of the detection resistor becomes a positive voltage, thereby forcibly turning off the low-side switching device.

Abstract: A power supply system of the present invention aims to achieve optimization of the efficiency and therefore includes: z (z is a natural number equal to or larger than 2) power supplies (PS-1 to PS-z) connected in parallel; and a controller (8) for the number of power supplies in operation which controls the number of power supplies in operation among the power supplies (PS-1 to PS-z).

Abstract: A CMOS IC according to the invention includes a discharging circuit for preventing electrostatic breakdown from occurring. The discharging circuit includes a discharging NMOSFET Qe, which couples a gate terminal node Vgp continuous to the gate of an outputting PDMOS transistor Qo and the gate of a discharging NMOSFET Qe via a capacitor Ce, and connects the drain of the discharging NMOSFET Qe to a gate terminal node Vgp continuous to the gate terminal of the outputting PDMOS transistor Qo. The discharging circuit 300 also includes a pull-down resistor disposed between the gate of the discharging NMOSFET Qe and the ground for preventing the discharging NMOSFET Qe from operating in a steady state condition. The CMOS IC according to the invention makes the discharging NMOSFET Qe trigger to operate by the potential change at the node corresponding to the potential change of the power supply line, when a surge caused by static electricity and such is applied to the power supply line.

Abstract: A switching power supply device that includes a feedback terminal to which a feedback signal according to a load state is input, and a comparator which compares a terminal voltage of the feedback terminal with a reference voltage and determines whether the load state is a normal load state or a light load state. The switching power supply device also includes pull-up resistors which are connected to the feedback terminal, a switch element which switches resistance values of the pull-up resistors according to the change of the load state, and a switch element which switches the resistance values of the pull-up resistors according to whether the input voltage is high or low.

Abstract: A CMOS IC according to the invention includes a discharging circuit for preventing electrostatic breakdown from occurring. The discharging circuit includes a discharging NMOSFET Qe, which couples a gate terminal node Vgp continuous to the gate of an outputting PDMOS transistor Qo and the gate of a discharging NMOSFET Qe via a capacitor Ce, and connects the drain of the discharging NMOSFET Qe to a gate terminal node Vgp continuous to the gate terminal of the outputting PDMOS transistor Qo. The discharging circuit 300 also includes a pull-down resistor disposed between the gate of the discharging NMOSFET Qe and the ground for preventing the discharging NMOSFET Qe from operating in a steady state condition. The CMOS IC according to the invention makes the discharging NMOSFET Qe trigger to operate by the potential change at the node corresponding to the potential change of the power supply line, when a surge caused by static electricity and such is applied to the power supply line.

Abstract: The voltage of a detection resistor connected to the drain of a low-side switching device is normally a negative voltage, but a positive voltage appears when a countercurrent occurs in an abnormal state. A current comparator monitors the voltage of the detection resistor, transmits high output to an AND circuit whole the voltage of the detection resistor is a negative voltage to maintain the output voltage of the current comparator in a low state when an output signal of a driver can be transmitted to the low-side switching device, and allows the output voltage of the current comparator in a low state when the voltage of the detection resistor becomes a positive voltage, thereby forcibly turning off the low-side switching device.

Abstract: The invention provides a bootstrap circuit which enables adequate charging of a capacitor used in the bootstrap circuit even during light load or no load conditions, and which does not impede the performance of a step-down converter proper, as well as a step-down converter using the bootstrap circuit. A capacitor charge/discharge path formation mechanism is provided in the bootstrap circuit that enables a terminal of a capacitor used in the bootstrap circuit to be separated and made independent from a step-down converter circuit.