582 results about "Smoothing circuits" patented technology

A low-cost PFC converter capable of detecting an inductor current including a DC component and performing appropriate correction of a power factor with low loss includes a diode bridge that rectifies an AC voltage input from an AC input power supply Vac, a series circuit including an inductor and a switching element, a rectifying and smoothing circuit that is connected in parallel to the switching element and that includes a diode and a smoothing capacitor, and a digital signal processing circuit that performs on / off control on the switching element so that an input current input from the AC input power supply Vac has a similar waveform with respect to an AC voltage. A current flowing through the inductor during an off period of the switching element is detected using a current detecting resistor, and a decreased voltage of the current detecting resistor is sampled at the middle of the off period of the switching element, thereby detecting an average value of the input current.

An improved circuit wiring layout provides smooth circuit wiring in a peripheral circuit region adjacent to a memory cell region of a semiconductor memory device, and eliminates a write-speed limiting factor. Forming a metal (instead of a metal silicided polysilicon) wiring layer to be connected to a gate layer, to transmit an electrical signal to the gates of FET (e.g., MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistors formed in the peripheral circuit region; the metal wiring layer is formed (e.g., using one metal damascene process), on a layer different from a word line layer formed on the gate layer (e.g., using another metal damascene process), thereby obtaining a layout of a peripheral circuit region having a reduced area and without using a silicide process.

Zero volt switching during a light load is performed in such a manner that through an ON / OFF control of switches provided for a full bridge circuit and the synchronous rectifier switches in a rectifier and smoothing circuit, a resonant peak voltage necessary for the zero voltage switching determined by the output current flowing to output terminals, a resonant inductor and a resonant capacitor capacitance is ensured so that an energy accumulated in the rectifier and smoothing circuit is returned to the full bridge circuit so as to act as equivalent as when the output current is increased and to increase the current flowing through the full bridge circuit.

A transformer has a primary winding connected between a pair of dc input terminals via a switch, a secondary winding connected between a pair of output terminals via a first rectifying and smoothing circuit, and a tertiary winding connected to a second rectifying and smoothing circuit for feeding a switch control circuit. Included in the switch control circuit is a switch control pulse generator circuit whereby the switch is driven to provide a constant dc voltage at the output terminals. A mode selector circuit is connected to the switch control pulse generator circuit to cause the switch to be driven continuously under normal load, and at intervals under light load. The intermittent driving of the switch is suspended, and the switch driven continuously, in the event of a drop in the output voltage of the second rectifying and smoothing circuit to a predefined value during operation in light load mode.

A series circuit in which a first switching element and a second switching element are connected in series at both ends of an output of an input rectifier circuit for rectifying an alternating current of an alternating current power supply, a resonant circuit in which a primary winding of a transformer and a current resonant capacitor are connected in series at both ends of the first switching element or the second switching element, a rectifying and smoothing circuit for rectifying and smoothing a voltage generated across a secondary winding of the transformer during an on-period of the first switching element or the second switching element, a control circuit for alternately turning on / off the first switching element and the second switching based on a voltage from the rectifying and smoothing circuit, and a voltage detecting circuit for outputting a voltage detecting signal when a voltage at both ends of one switching element of the first switching element and the second switching element, which is turned on at a time of transmitting electric power to the rectifying and smoothing circuit, becomes equal to a predetermined voltage or more. The control circuit turns on the other switching element of the first switching element and the second switching element based on the voltage detecting signal from the voltage detecting circuit.

A power factor corrector is connected to an AC power source, to provide a first DC voltage. A DC-DC converter supplies the first DC voltage from the power factor corrector to a primary winding of a transformer. A first rectifying / smoothing circuit rectifies and smoothes a voltage generated by a secondary winding of the transformer and supplies the rectified-and-smoothed voltage to a load. A second rectifying / smoothing circuit rectifies and smoothes a voltage generated by a control winding of the transformer. A light-load detector detects if an output ripple of the second rectifying / smoothing circuit is equal to or greater than a predetermined value, determines upon detection that the switching operation has decreased the frequency thereof or has shifted to an intermittent oscillation, and stops the power factor corrector.

A DC-DC converter of the present invention includes: an activation circuit which activates a control circuit for controlling a turning on and off of a switching element; a second rectifying and smoothing circuit which supplies an output voltage, as a power supply, to the control circuit, the output voltage being obtained by rectifying and smoothing a voltage in a tertiary winding of a transformer; an overcurrent protection circuit which limits an output current to be supplied to a load when overloaded; an overcurrent detection circuit which detects that the load is in an overcurrent state, and which outputs a detection signal during a period when the overcurrent protection circuit is operated; and an activation current switching circuit which switches outputs from the activation circuit.

A switching power supply circuit includes a transformer having a primary winding, a secondary winding, and a feedback winding, a switching element connected in series to a first of the primary winding, a control circuit disposed between a control terminal of the switching element and the feedback winding, a starting circuit connected between a second end of the primary winding and the control terminal of the switching element, and a rectifying / smoothing circuit connected to the secondary winding. The control circuit includes a first delay circuit for determining the time that elapses before the switching element is turned on by a voltage generated at the feedback winding, a control element driven to prevent the switching element from turning on or forcibly turn off the switching element, and a second delay circuit for changing a delay time such that, under rated load or under heavy load, the switching element is turned off by driving the control element after the switching element is turned on by the voltage generated at the feedback winding, and, under light load, the turn-on of the switching element is blocked by driving the control element before the switching element is turned on by the voltage generated at the feedback winding.

A switching power supply device that can reduce switching loss to obtain high efficiency. Additionally, the number of components of control circuits and the cost of switching elements can be reduced, with a transformer made compact and lightweight. In this switching power supply device, one end of a series circuit comprising a primary winding of the transformer, an inductor, and a capacitor is connected to a junction of a first switching circuit and a second switching circuit. The other end of the series circuit is connected to an input power source. A secondary winding of the transformer is connected to a rectifying and smoothing circuit including a rectifying element. In addition, in order to perform a self-excited oscillation, there are arranged first and second control circuits. The first control circuit controls a time elapsing until the first switching circuit turns on after the generation of a voltage in a first driving winding of the transformer and a time elapsing until the first switching circuit turns off. Similarly, the second control circuit controls a time elapsing from the generation of a voltage in a second driving winding of the transformer to the turn-on of the second switching circuit and a time elapsing until the second switching circuit turns off.

An LED driving circuit includes a dimming circuit that controls a conducting angle of an alternating current supplied from a power supply to phase-control a current to be supplied to an LED, a rectifier circuit that rectifies an alternating-current voltage output from the dimming circuit, a smoothing circuit that smoothes a direct current voltage output from the rectifier circuit, a switching device that is connected with the LED in series; a constant current control circuit that outputs a high frequency pulse signal to the switching device to control the switching device, and a bleeder circuit that is provided between an output terminal of the rectifier circuit and a ground and that has a bleeder resistance and a bleeder switch connected in series. The high frequency pulse signal is input to the bleeder switch so that a bleeder current having a high frequency pulse form flows in the bleeder resistance.

A buck-boost converter includes: a buck converter section including a first switch, a first rectifier, and an inductor; a boost converter section sharing the inductor and including a second switch, a second rectifier, and a smoothing circuit; and a control circuit for generating and outputting a first driving signal for opening and closing the first switch and a second driving signal for opening and closing the second switch. The control circuit includes: an error amplifier circuit for amplifying an error between an output value from the smoothing circuit and a predetermined voltage value to thereby generate and output an error signal; an oscillator circuit for generating and outputting a triangular wave signal having a predetermined cycle; a compensatory signal generation circuit for generating and outputting a compensatory signal, which oscillates in a cycle that is at least twice the cycle of the triangular wave signal; a control signal generation circuit for adding together the error signal and the compensatory signal to thereby generate and output a control signal; and a comparator circuit for comparing the triangular wave signal with the control signal to generate and output the first or second driving signal.

A switching power supply includes a switching circuit, a main transformer, a rectifier circuit, and an output smoothing circuit, which are mounted on a base plate. Voltage transformation of an inputted direct current voltage is performed through collaboration among the above. A pedestal portion is formed on the base plate, and a channel to cool down electronic parts such as a diode is formed inside the pedestal portion. Since the channel is thus formed inside the pedestal portion, the device will not be larger-sized even when the channel is formed. Moreover, at least any of a switching element and a diode is mounted on the pedestal portion, and a choke coil is mounted in a region other than a region where the pedestal portion is formed. Therefore, even with the pedestal portion, it is significantly suppressed for the device to be larger-sized.

There is provided a high-efficiency DC-DC converter which comprises a voltage resonance circuit to which electric power from a low-voltage direct-current power supply, including a household fuel cell and a solar cell, is input and performs DC-AC conversion by zero-voltage switching, an insulating high-frequency transformer which transmits the converted power, a current resonance circuit which is provided on the secondary side of the transformer and performs zero-current switching, a rectifier circuit which rectifies the output from the current resonance circuit, and a smoothing circuit which rectifies the output from the rectifier circuit.

A DC conversion apparatus includes a plurality of current resonant converters. Each of the current resonant converters has two switching elements connected in series, a transformer having primary and secondary windings, a series resonant circuit including a resonant reactor, the primary winding of the transformer, and a resonant capacitor, and a rectifying circuit to rectify a voltage generated by the secondary winding of the transformer. The DC conversion apparatus also includes a smoothing circuit having a reactor L3 and a smoothing capacitor C and arranged after connection points to which output terminals of the rectifying circuits of the plurality of current resonant converters are commonly connected. The DC conversion apparatus further includes a controller to control, according to an output voltage from the smoothing circuit, ON / OFF of the two switching elements of each of the plurality of current resonant converters.