Abstract: A transformer that realizes ZVS operation includes a primary winding and a secondary winding. A control circuit turns switching elements on and off in a complimentary manner in order to repeatedly invert the voltage applied to the primary winding. A conduction path supplies a voltage excited in the secondary winding to a load connected between a high-potential side and a ground side of the secondary winding. A first rectifier diode has a rectification direction extending from the high-potential side toward the ground side of the load and is provided along the conduction path. A second rectifier diode and a capacitor, which are connected in series with each other, are connected in parallel with the secondary winding. An inductor is connected in parallel with the second rectifier diode. A rectification direction of the second rectifier diode matches the direction extending from the high-potential side to the ground side.

Abstract: In a switching power supply device, a partition portion that includes a slit divides a winding portion of a bobbin. A primary winding of a transformer is wound to a height h1 in a first section, and a secondary winding is wound to a height h2 in a second section. A low side drive winding and a high side drive winding are wound around the primary winding to a height h3 with the high side drive winding being located toward the secondary winding.

Abstract: In a switching power supply apparatus, when it is detected at time t1 that a voltage Vis has exceeded a first threshold Vth1, a timer counting a period of time T1 is started, and the number times the input voltage Vis does not exceed Vth1 is started to be counted. When the timer expires before the count reaches a predetermined number, a first overcurrent protection operation is performed. When it is detected at time t2 that Vis has exceeded a second threshold Vth2, a second overcurrent protection operation is immediately performed. As a result, appropriate overcurrent protection is performed in accordance with the operating state of a load.

Abstract: A power transmitting unit-side resonance circuit including a resonance capacitor connected in series to a power transmitting coil and a power receiving unit-side resonance circuit including a resonance capacitor connected in series to a power receiving coil are caused to resonate with each other so that each resonance circuit resonates. With this, power is transmitted between the power transmitting coil and the power receiving unit making use of magnetic field resonance coupling and electric field resonance coupling. By making use of resonance, only effective power is transmitted from the power transmitting unit side to the power receiving unit side, while reactive power that is reflected is reserved as resonance energy in each resonance circuit.

Abstract: A switching power supply apparatus includes an isolated converter that has efficiency characteristics in which power conversion efficiency at a rated load is higher than power conversion efficiency at a light load and that converts power-supply voltage into direct-current voltage to output the direct-current voltage; an FET that switches supply and shutoff of the power-supply voltage to the isolated converter; a secondary battery that stores the direct-current voltage output from the isolated converter; a voltage detector that detects an amount of charge in the secondary battery; and a controller that switches the FET on the basis of the amount of charge in the secondary battery.

Abstract: A switching power supply apparatus includes an isolated converter with efficiency characteristics in which power conversion efficiency of a rated load is higher than power conversion efficiency of a light load and that converts power-supply voltage into direct-current voltage to output the direct-current voltage, a secondary battery that stores the direct-current voltage output from the isolated converter; a voltage detector that detects an amount of charge in the secondary battery; and a controller that switches driving and stopping of the isolated converter on the basis of the detected amount of charge.

Abstract: In an AC power supply apparatus, first and second switching circuits connected in series to an input terminal to which a DC input power supply is connected include first and second rectification elements, respectively. A capacitor, an inductor, and a capacitive load are equivalently connected in series to the second switching circuit. The capacitor is charged after the first switching circuit is turned on before the second rectification element is turned off and the charged capacitor is caused to discharge after the second switching circuit is turned on before the second rectification element is turned off. The above operations are periodically repeated. The voltage of the capacitive load is reversed with current flowing during the charge and the discharge of the capacitor to adjust the on and off periods of the first and second switching circuits in order to supply desired AC voltage to the capacitive load.

Abstract: A primary side resonant circuit is formed by a primary side resonant inductor and a primary side resonant capacitor, and secondary side resonant circuits are formed by secondary side resonant inductors and secondary side resonant capacitors. Equivalent mutual inductances and equivalent mutual capacitances are formed through electromagnetic field resonant coupling between a primary winding and secondary windings, and a multi-resonant circuit including an LC resonant circuit formed in each of the primary side and the secondary side is formed. Electric power is transmitted from the primary side circuit to the secondary side circuit, and resonant energy that is not transmitted from the primary winding and, of energy which the secondary winding has received, resonant energy that is not supplied to an output are each retained in the multi-resonant circuit.

Abstract: In a switching power-supply apparatus, a primary-side power converter circuit includes a half bridge system and a synchronous rectifier circuit is provided as a rectifier circuit of a secondary-side power converter circuit. An on time ratio of the on time of a first switching element to the on time of a second switching element is controlled so as to provide an operation mode in which energy is regenerated from the secondary side to the primary side when the load is light.

Abstract: In a switching power supply device, a voltage of a counter electromotive force induced in a drive winding as a high side switching element is turned off is output to a ZT terminal of a switching control IC, and thus an OUT terminal of the switching control IC is brought to a high level, and thus a low side switching element is turned on. A constant current circuit charges a capacitor with a constant current through a voltage at the OUT terminal. A comparator in the switching control IC inverts the voltage at the OUT terminal to a low level upon a voltage at an IS terminal exceeding a voltage at an FB terminal. Thus, an on time of the low side switching element is controlled in accordance with a voltage output to the FB terminal, and an output voltage Vo is turned into a constant voltage.

Abstract: A primary side resonant circuit is formed by a primary side resonant inductor and a primary side resonant capacitor, and secondary side resonant circuits are formed by secondary side resonant inductors and secondary side resonant capacitors. Mutual inductances are formed equivalently through magnetic field resonant coupling between a primary winding and secondary windings, and a multi-resonant circuit that includes two or more LC resonant circuits is formed by a primary side circuit and a secondary side circuit. Electric power is transmitted from the primary side circuit to the secondary side circuit; resonant energy that is not transmitted from the primary winding and, of energy which the secondary winding has received, resonant energy that is not supplied to an output are each retained in the multi-resonant circuit; and, at the secondary side, the resonant energy is retained in a current path in which a rectifying element is not formed in series.

Abstract: In a switching power supply apparatus, a first switching element is controlled by a driving voltage output from a switching control IC. A second switching control circuit controls the on-time of a second switching element so that the time ratio of the on-time of the second switching element to the on-time of the first switching element becomes almost constant with respect to a change in a load current. In a normal load state, since a square wave output from a frequency setting unit within the switching control IC is output with no change, a converter operates in a current-continuous mode. In a light load state, a driving signal generation unit within the switching control IC is subjected to blanking with the period of a signal output from a maximum frequency setting unit and an oscillation frequency is reduced. Accordingly, the converter operates in a current-discontinuous mode.

Abstract: In a power supply apparatus driving circuit, at startup, an input voltage of a switching power supply is used as a driving power supply, and loss generated in a starting circuit is reduced. The starting circuit and the driving circuit are configured as a single driver. A control IC generates a switching control signal to control a first switching element and a second switching element. A driving circuit in a high breakdown voltage driver IC generates gate drive voltage signals for the first switching element and the second switching element based on the switching control signal inputted from the control IC. A starting circuit supplies the partial voltage of a voltage inputted to a starting power supply terminal, to each of the driving circuit in the high breakdown voltage driver IC and the control IC that is externally provided, and shuts off a switching element after startup.

Abstract: In a switching control circuit, a length of a soft start period is set by a time constant of an external circuit that is connected to a soft start terminal of a switching control IC. After a voltage of the soft start terminal has reached a predetermined voltage at the termination of the soft start period, the on-pulse period of a first switching device is limited by a maximum value. When a Zener diode is connected between the soft start terminal and ground, the upper limit voltage of the soft start terminal is a Zener voltage and, hence, the maximum on-pulse period is limited by this voltage. As a result, the switching control circuit and a switching power supply apparatus, which have a soft start function and a power limiting function, are reduced in size and cost by limiting the number of terminals.

Abstract: A switching power-supply apparatus and a switching power supply circuit in which a feedback signal is input from a feedback circuit to a feedback terminal of a switching control IC includes a capacitor and a Zener diode connected between the feedback terminal and a ground terminal. The Zener diode is a selectively connected external circuit. A voltage of the feedback terminal during an overcurrent operation changes depending on whether or not the external circuit is present. A return/latch determination circuit detects the voltage of the feedback terminal to switch between an automatic return system and a latch system in an overcurrent operation state.

Abstract: A switching power supply apparatus includes a low-side switching control unit and a high-side switching control unit. The low-side switching control unit includes a low-side turn-off circuit that turns off a low-side switching element behind a delay time when reversal of the polarity of a winding voltage of a transformer is detected during a period in which a drive voltage signal is supplied to the low-side switching element. The high-side switching control unit includes a high-side turn-on delay circuit that delays a time from the time when the polarity of the winding voltage of the transformer is reversed to a time when a high-side switching element is turned on. The delay time of the low-side turn-off delay circuit is set so as to be shorter than the delay time of the high-side turn-on delay circuit.

Abstract: In a switching power supply apparatus, a comparator outputs a first determination criterion signal based on a saw-tooth wave signal whose level fluctuates with a constant period and a detection voltage signal. An inverter subjects the first determination criterion signal to reverse processing, and outputs a second determination criterion signal. The comparator outputs a first switching judgment-use signal from a monitor signal and a threshold value, and the comparator outputs a second switching judgment-use signal from the monitor signal and the threshold value. An AND circuit outputs the first switching control signal from the first determination criterion signal and the first switching judgment-use signal, and the AND circuit outputs the second switching control signal from the second determination criterion signal and the second switching judgment-use signal.

Abstract: A switching control IC conducts on-off control on a first switching element. A second switching control circuit is provided between a high-side driving winding of a transformer T and a second switching element. The second switching control circuit discharges a capacitor in a negative direction with a constant current during an on period of the first switching element, and then after the second switching element is turned on, charges the capacitor in a positive direction with a constant current. A transistor controls the on period of the second switching element in accordance with the ratio of a charging current to a discharge current such that the ratio of the on period of the second switching element to the on period of the first switching element is substantially always constant.

Abstract: In a switching power supply device with reduced size and increased power conversion efficiency, a secondary-side rectifier circuit includes an adder-rectifier circuit that stores a voltage generated in a secondary winding in a capacitor as electrostatic energy in an on period of one of a high-side and low-side switching circuits or, and adds the voltage in the capacitor and the voltage generated in the secondary winding and outputs the sum as a direct-current voltage during in an on period of the other of the high-side and low-side switching circuits. A switching control circuit adjusts an output power to be output from the secondary-side rectifier circuit, by using on-period ratio controller that controls a proportion of periods during which the respective high-side side and low-side switching elements are brought into a conductive state.

Abstract: A power-transmission-unit-side resonant circuit includes a resonant capacitor connected in series with a power transmission coil and a power-reception-unit-side resonant circuit including a resonant capacitor connected in series with a power reception coil resonate with each other to cause sympathetic vibration. This allows power to be transferred using two kinds of coupling via the magnetic field and the electric field between the power transmission coil and the power reception coil. Also, operation is performed at a switching frequency that is higher than a specific resonant frequency of the entire multi-resonant circuit, such that a ZVS operation is performed. As a result, a switching loss is reduced by a large amount and a highly efficient operation is performed thus enabling a power transfer system with a reduced size and an increased power conversion efficiency to be provided.