Abstract: A rectification switch control switch element (Q7) is provided between a gate and a source of a rectification switch element (Q2). The rectification switch control switch element (Q7) is turned ON in response to a signal on a secondary side of a pulse transformer (T2) at a turn OFF timing of a main switch element (Q1) to forcedly turn OFF the rectification switch element (Q2). As a result, the rectification switch element (Q2) can be turned OFF in synchronism with an OFF of the main switch element at a time of a backflow. With use of a free resonance between a capacitance between a gate and a source of the rectification switch element (Q2) and a commutation switch element (Q3) and a choke coil (L2), an excitation state of the choke coil (L2) can be reset. Then, it is possible to stabilize a detection voltage of a tertiary rectification smoothing circuit (22) which uses a tertiary winding (N13) of a transformer (T1), thus stabilizing control of the circuit functions.

Abstract: A switching power supply circuit includes a direct current (DC) power supply input; a voltage divider connected between the DC power supply input and ground; a transformer including a primary winding, a secondary winding, and an assistant winding; a pulse generating circuit including a first transistor, a second transistor, an oscillation capacitor, and an oscillation resistor; an output; and a feedback circuit adjusting a duty ratio of a pulse signal in the assistant winding. The DC power supply input is grounded via the primary winding, two conducting electrodes of the second transistor. A control electrode of the second transistor is connected to an output of the voltage divider. An output of the voltage divider is connected to a control electrode of the second transistor and is grounded via two conducting electrodes. A control electrode of the first transistor is grounded via the assistant winding and grounded via the oscillation capacitor and the oscillation resistor connected in series.

Abstract: Disclosed is a synchronous forward converter having a reverse current suppressor connected to the gate of a freewheel switch. The reverse current suppressor is configured to receive a control input signal generated by an internal circuitry of a power supply system where the forward converter locates, such as an enable signal, to detect the power-off of the forward converter, and in response thereto turn off the freewheel switch during the interruption of the input power of the forward converter. Alternatively, the reverse current suppressor is configured to detect the decay of the input voltage across the input bulk capacitor located on the primary side of a transformer of the forward converter, and turn off the freewheel switch when the voltage across the secondary side of the transformer is decayed to be smaller than the output voltage of the forward converter.

Abstract: A discontinuous resonant forward power converter including a controller having an output coupled to a controllable switch and which is configured to control the switch such that a voltage waveform on a secondary winding of a transformer of the converter has a first portion during which the switch is on and current flows into an output node of the converter which is coupled to the output rectifier and to a smoothing capacitor, and which has a second substantially resonant portion during which the switch and an output rectifier are both off. Substantially no current flows into the output node during the second portion of said voltage waveform.

Abstract: The present invention is directed to a switch mode power converter for supplying an output power to a load, which includes a switching device having a switching input, a switching output, and a control input for enabling or disabling the switching device from conducting current from the switching input to the switching output. The converter also includes a network in which the switching device input, the switching device output, and the load are connected together to form a circuit. The converter also includes a bias winding in the circuit for producing a bias voltage representative of the output power, and a control circuit. The control circuit is for (a) determining the rate of change of the bias voltage, (b) characterizing the rate of change, and (c) controlling the control input as a result of the characterization (b).

Abstract: Power converter for receiving an input current at an input voltage and for providing an output current at an output voltage. The power converter comprises a transformer (133) having a primary (136) and at least one secondary (138) side, wherein the transformer shows a mutual inductivity Ls. The power converter further comprises at least one switching device (124a, 124b) being operated at an operating frequency fop at the primary side of said transformer, and a capacitor CS at the primary side of the transformer. The capacitor forms a resonant circuit with the leakage inductivity LS of said transformer, wherein said operating frequency, said capacitor Cs, said mutual inductivity Lm and said leakage inductivity LS are matched such that the effective value of the output current is substantially constant with respect to variations of a load being traversed by said output current by using resonance principles and operating the power converter in a current source mode.

Abstract: A switching power source apparatus includes a switching element connected through a primary winding of a transformer to a DC power source, a start circuit for a control circuit, a rectify-smooth circuit of a voltage of a secondary winding of the transformer, and a rectify-smooth circuit to rectify and smooth a voltage of a tertiary winding of the transformer into a source voltage for the control circuit. The start circuit supplies a first starting current to start the apparatus and stops the first starting current once the apparatus has started. If the source voltage to the control circuit decreases to a turn-off voltage after the apparatus has started, the start circuit supplies a second starting current that is smaller than the first starting current. If the source voltage to the control circuit further decreases to a predetermined voltage that is lower than the turn-off voltage, the start circuit supplies the first starting current.

Abstract: Provided herein is a power factor correction (PFC) power supply, comprising: a bridge rectifier having an input and an output, a filter capacitor connected to the output of the bridge rectifier, a transformer having a primary winding, a fly-back winding and a secondary winding, a forward diode, a fly-back diode, a storage capacitor circuit having a valley-fill circuit and a capacitor connected in parallel, and a switch connected between the primary winding and the output of the bridge rectifier. The PFC power supply features improved efficiency and low switching loss.

Abstract: A switching mode power supply and method for generating a bias voltage is described. The bias voltage is generated by using a current source coupled to a primary coil of a transformer during the start-up of the switching mode power supply. The generation of the bias voltage through the current source is stopped at a second time, a delay time after a first time when the bias voltage becomes essentially equal to a reference voltage that is an operational voltage of a PWM controller. The switching operation of a main switch is started after the first time, when the bias voltage exceeded the operational voltage. In this interval the bias voltage is also generated by the secondary coil of the transformer.

Abstract: A modification of a control loop of a primary side sensing power control system that uses a different and unique relationship to accomplish the constant current control while attenuating the affects of a ripple voltage.

Abstract: A stabilized power supply for X-ray tubes having a first rectifier circuit, an inverter circuit comprising main switches, a transformer, a second rectifier circuit an oscillation circuit and an inverter circuit. The power supply includes an auxiliary circuit that can be driven and is parallel-connected to the oscillation circuit. The auxiliary circuit duplicates changeover switching times of the switches of the inverter in order to limit an overlapping phenomenon that occurs for these switches during the changeover switching operations.

Abstract: The present invention is a system and a method that controls the current limit such that it is maintained within a small range for any acceptable input voltages, e.g., 90 to 264 Volts RMS, causes the output voltage of a PWM controller to drop as the output load increases so as to maintain a constant current output, and does cycle by cycle calculation compensating for the VIN ripple output from the bridge and bulk filter capacitor so that no loop filter is required in the constant current mode.

Abstract: There is provided a power supply for AC/DC and DC/DC conversion which receives the DC power supplied from airplanes, vehicles and vessels as well as normal AC power, and converts the power to DC power and supplies it to portable electronic products. The power supply for AC/DC and DC/DC conversion includes an AC input 10, a DC input 20, a switch 30 for selecting AC input power or DC input power, a DC output 40, and a circuit used for AC/DC and DC/DC conversion 100 which converts the power input from the AC input or the DC input to DC power having predetermined values of current and voltage, and a secondary side of a transformer (TL) for AC/DC conversion inside the circuit for conversion serves as an inductor for performing DC/DC conversion.

Abstract: An exemplary direction current (DC) to DC converter includes a first rectifying and filtering circuit configured to receive an alternating current (AC) voltage and transform the AC voltage to a first DC voltage, a pulse width modulation (PWM) circuit, a first transformer configured to receive the first DC voltage and transform the first DC voltage to a second AC voltage under control of the PWM circuit, and a second rectifying and filtering circuit including a first transistor and a control circuit for switching on or switching off the first transistor so as to transform the second AC voltage to a second DC voltage.

Abstract: System and method for providing control for switch-mode power supply. According to an embodiment, the present invention provides a system for regulating a power converter. The system comprises a signal processing component that is configured to receive a first voltage and a second voltage, to process information associated with the first voltage and the second voltage, to determine a signal based on at least information associated with the first voltage and the second voltage, and to send the signal to a switch for a power converter. The switch is regulated based on at least information associated with the signal. The signal processing component is further configured to determine the signal to be associated a first mode, if the first voltage is higher than a first threshold.

Abstract: In one embodiment, a switching power supply controller decouples the power supply controller from receiving a sense signal during one portion of the operation of the power supply controller and couples the switching power supply controller to receive the sense signal during another portion of the operation.

Abstract: A secondary-side rectifying and smoothing circuit rectifies and smoothes an output voltage from a secondary coil of a transformer and outputs a rectified and smoothed voltage to the outside. A tertiary-side rectifying and smoothing circuit rectifies and smoothes an output voltage from a tertiary coil to produce a direct-current voltage and detects and outputs the direct-current voltage as a detected voltage of the output voltage from the secondary-side rectifying and smoothing circuit. A control circuit controls the switching operation of a main switching device on the basis of the detected voltage so that the output voltage is stabilized. The secondary-side rectifying and smoothing circuit includes a rectification-side synchronous rectifier and a commutation-side synchronous rectifier as rectifying devices.

Abstract: A power converter has a transformer including a primary winding connected between a power input and a power switch, the power switch is switched to deliver power from the power input to a power output, an auxiliary winding provides an induced voltage in such a manner that when the power switch is at a first switch state, the induced voltage reflects an input information of the power converter, and when the power switch is at a second switch state, the induced voltage reflects an output information of the power converter. Two detection signals are generated from the input and output information, respectively, to implement multiple functions and protections.

Abstract: A primary side sensing power control system and method for constant current control that utilizes a relationship that involves the measured reset-time from the previous cycle to determine the primary side peak current and off-time for the next cycle. This control mechanism does not need the knowledge of input voltage or magnetizing inductance. Therefore, it removes the sensitivities of input voltage and magnetizing inductance to the output current limit. Furthermore, it uses a time measurement instead of a voltage measurement for the current calculation which in many cases is easier to perform.

Abstract: This invention relates to a control circuit for the closed-loop control of an output voltage of a primary-controlled switched-mode power supply as well as an associated method. The switched-mode power supply comprises a primary-side switch and a transformer with at least one auxiliary winding in which an auxiliary voltage is induced after opening the primary-side switch. The voltage induced in the at least one auxiliary winding provides the basis for the measurement voltage passed to the control circuit and for the supply voltage of the control circuit. The invention also refers to an associated switched-mode power supply.

Abstract: A controller controls the output current by measuring and controlling the switching current of the power converter. A first circuit generates a first signal in accordance with the switching current. A second circuit detects a discharge-time of the transformer. A third circuit generates a third signal by integrating the first signal with the discharge-time. The time constant of the third circuit is programmed and correlated with the switching period of the switching signal, therefore the third signal is proportional to the output current. A switching circuit generates a switching signal and controls the pulse width of the switching signal in accordance with the third signal and a reference voltage. Therefore, the output current of the power converter can be regulated.

Abstract: The invention finds application in the field of power supplies for valve actuators, and particularly relates to a wide voltage range stabilized switching power supply for valve actuators, of the type that comprises a filter 2, a diode bridge 3, an array of capacitors 5, an auxiliary power supply stage 6, formed by a switch mode circuit, having an operating range of 21 to 380 VDC, which generates the supply voltages required for the internal operation of the power supply, a full-bridge power stage 7, which receives an input voltage in the range of 120 VDC to 373 VDC, and generates the three stabilized output voltages required for supplying the load, and a boost stage 4, located upstream from the power stage 7, which allows to increase the voltage to a value in the range of 120 VDC to 373 VCC, whenever it is below such range.

Abstract: A primary side sensing power control system and method for constant current control that utilizes a relationship that involves the measured reset-time from the previous cycle to determine the primary side peak current and off-time for the next cycle. This control mechanism does not need the knowledge of input voltage or magnetizing inductance. Therefore, it removes the sensitivities of input voltage and magnetizing inductance to the output current limit. Furthermore, it uses a time measurement instead of a voltage measurement for the current calculation which in many cases is easier to perform.

Abstract: The present invention provides a synchronous switching control circuit for variable switching frequency power converters. It comprises a first circuit to generate a first signal in response to an input synchronous signal of a power converter. A second circuit is coupled to the first circuit to generate a second signal in accordance with the frequency of the first signal. Only when the first signal is operated in a specific frequency range, the synchronous operation is allowed. An oscillation circuit is connected to the first circuit and the second circuit to receive the first signal and the second signal to generate an oscillation signal. The oscillation signal is utilized to enable the switching signal of the power converter. The switching signal is thus synchronized with the input synchronous signal in response to the enable of the second signal. Otherwise, the switching signal will be free running.

Abstract: The present invention refers to a control circuit and an associated method of controlling the output voltage of a primarily controlled power switching supply with a primary-sided switch and a transformer with an auxiliary winding, in which after opening the primary-sided switch an auxiliary voltage for indicating the output voltage is induced. The induced voltage is supplied to a control circuit as control variable.

Abstract: A regulator may include a load voltage sensing circuit configured to generate a feedback signal representative of output voltage from an isolated flyback converter. The regulator may include a pulse generator configured to controllably generate the pulses and to increase at least one off time and at least one period of the pulses after a load on the flyback converter decreases.

Abstract: A bootstrap circuit for switching power supplies (SMPS), a switching power supply including a bootstrap circuit, and an integrated circuit of a switching power supply, are provided. The bootstrap circuit (13) for switching power supplies includes a first supply voltage (Vin) coming from a first terminal and a second supply voltage (Vcc) coming from a second terminal and a third terminal (30). The bootstrap circuit includes: a first current path between the first terminal and the third terminal (30); a second current path between the first terminal and the second terminal; a third current path between the second terminal and the third terminal (30); and a two-way voltage regulator (M3, Dz2, R5, R6) placed along the second current path.

Abstract: A stabilized power supply for X-ray tubes having a first rectifier circuit, an inverter circuit comprising main switches, a transformer, a second rectifier circuit an oscillation circuit and an inverter circuit. The power supply includes an auxiliary circuit that can be, driven and is parallel-connected to the oscillation circuit. The auxiliary circuit duplicates changeover switching times of the switches of the inverter in order to limit an overlapping phenomenon that occurs for these switches during the changeover switching operations.

Abstract: A capacitor charging circuit does not include a Zener diode and makes it possible to integrate a large number of circuits and elements within a semiconductor integrated circuit. The capacitor charging circuit includes a flyback transformer having a primary coil, a secondary coil, and a tertiary coil, a switching element that turns the current that flows through the primary coil on and off, a capacitor that is charged by a current produced in the secondary coil through the on-off action of the switching element, and a charge control circuit that controls the on-off action of the switching element. When the switching element is off and a voltage produced at a first end of the tertiary coil is larger than a reference voltage corresponding to the predetermined voltage of the charge voltage of the capacitor, the on-off action of the switching element is stopped.

Abstract: A DC converter has a transformer with loosely coupled primary and secondary windings, a main switch connected in series with the primary winding of the transformer, and a series circuit connected to ends of one of the primary winding and main switch. The series circuit includes a clamp capacitor and an auxiliary switch. The main and auxiliary switches are alternately turned on/off so that a voltage of the secondary winding of the transformer is synchronously rectified with synchronous rectifiers and is smoothed with smoothing elements, to provide a DC output. The DC converter also includes a tertiary winding tightly coupled with the primary winding of the transformer, a voltage source to supply a voltage lower than a voltage generated by the tertiary winding of the transformer, and clamp diodes to clamp the voltage generated by the tertiary winding with the use of the voltage source. The clamp diodes provide voltage-clamped signals to drive the synchronous rectifiers.

Abstract: The present invention relates to a method for controlling the output voltage of a primary-controlled switched-mode power supply unit having a primary-side switch and a transformer with an auxiliary winding in which an auxiliary voltage which images the output voltage is induced after the primary-side switch is opened. The voltage induced in the auxiliary winding is fed to a control circuit as the control variable. The present invention also relates to a control circuit for performing such a control method and to an associated switched-mode power supply unit. To adjust the output voltage and the output current in the simplest and most economical way while minimizing the cost of the components needed, the switching frequency of the primary-side switch is so adjusted in dependence on the auxiliary voltage in the present invention that the output voltage and the output current of the switched-mode power supply unit adopt values in accordance with a predetermined output characteristic.

Abstract: There is provided an output voltage stabilizer for stabilizing an output voltage of a switching mode power supply by elimination power bounce appearing on the output voltage of the switching mode power supply. The output voltage stabilizer mainly includes a voltage comparator that compares a rectified DC voltage obtained by the rectification of an input AC voltage with a reference voltage and in response thereto generates an output signal, and a control switch that is biased according to the output signal of the voltage comparator and provides the power supply a drive signal to stabilize an output voltage of the power supply during the brownout or soft-start stage in the input AC voltage.

Abstract: A load control device includes a control circuit and a protection circuit. The control circuit controls driving of an electric load. The protection circuit monitors a power supply voltage supplied to the control circuit and stops control of driving the load by the control circuit, when the power supply voltage drops below a threshold value. The protection circuit provides the threshold value with a hysteresis characteristic having a width determined by a product of a wiring resistance of a path for supplying a driving current to the load and a maximum value of the driving current.

Abstract: A power factor is improved using a simplified structure without particularly providing a power factor improving circuit, and high efficiency is obtained.

Abstract: The present invention discloses an improved passive power filter circuit, wherein a rated compensating voltage is provided for the power factor compensating circuit in order to solve the problem of instable power output resulting from that the rated voltage is obtained via bypassing the standby power supply circuit in the conventional technology. Further, in the present invention, a circuit is used to pre-charge two filter capacitors, which are coupled to the DC output terminals of a rectifier, in order to offset the current phase advance or the current phase lag, which the conventional passive power filter circuit cannot solve, and thereby, the power factor is improved.

Abstract: In one embodiment, a switching mode power supply (SMPS) include: a power supply for supplying power to a secondary coil of a transformer according to an operation of a main switch, the main switch being coupled to a primary coil of the transformer; a feedback circuit for generating a feedback voltage corresponding to an output voltage; a control module for stopping the main switch when the feedback voltage is lower than a reference voltage in a standby operation mode; an integrated circuit (IC) power unit for generating a constant voltage, the IC power supply being coupled to the secondary coil of the transformer; and a current generator for using the constant voltage to generate a plurality of constant currents for operating a plurality of ICs, and generating a constant current from among the constant currents when the main switch performs no switching on/off operation.

Abstract: The invention relates to an electronic ballast for lamps having a converter, in which a switching transistor is protected against transient disturbances by a detection circuit C1, C2, R1, R2, D1–3, T1. In this case, the time derivative of the voltage is taken into consideration.

Abstract: A solid state switching circuit utilizes a transformer in series with the circuit's switching device by which energy initially stored in the primary of the transformer is recovered in resonant circuitry connected to the secondary of the transformer for transfer of the energy to the load when the switching device is not conducting.

Abstract: A circuit is provided for converting power from an AC power source to DC power. The circuit including bi-directional switches capable of conducting and blocking a current flow in both directions. One or more control switches are coupled to a bi-directional switch to enable and disable the current flow through the bi-directional switch, the control switches are controlled by a signal voltage to turn a bi-directional switch ON by discharging a threshold voltage on one of the bi-directional switch gates and turning a bi-directional switch OFF when the threshold voltage is not discharged by the control switches. Additionally, the circuit includes a transformer having one or more primary windings and a secondary winding, each primary winding being coupled to one of the bi-directional switch sources. The current flow through the primary winding is disabled when the current flow through the corresponding bi-directional switch source is disabled.

Abstract: A switch-mode self-coupling power device additionally increases a set of high voltage auxiliary winding in the transformer and increases a control circuit and an energy transmitting circuit in the primary side circuit of the conventional circuit. When the load is too low, the control circuit may control the energy transmitting circuit according to the variation of the load so that the voltage of the high voltage auxiliary winding can be transmitted to a controller for operation through the energy transmitting circuit. Therefore, the design of PWM controller (pulse width modulation controller) auxiliary power circuit according to the present invention, which is not limited by the magnitude of a dummy load at the secondary side of the transformer, can conform to international regulations and is a product with industrial purpose and conforming to green mode.

Abstract: An AC power supply supplied from an outlet 11 is rectified by a rectifying circuit 13 through an input filter 12. The rectified power is supplied to a primary winding N1 of a transformer 14. A controlling circuit 19 has a switching device Q1 that controls on/off at predetermined timing. An FB signal that represents a power state of a load circuit 15 is supplied to the controlling circuit 19 through a transistor Q2. A comparator 20 compares a rectified voltage V3 of a tertiary winding of the transformer with a reference voltage REF3 and outputs an error signal. With the error signal, the transistor Q2 is controlled. Thus, the voltage for the controlling circuit supplied from the tertiary winding can be prevented from lowering against abrupt load variation. In addition, the output voltage Vo can be prevented from largely varying.

Abstract: A half-bridge-type control signal generating circuit outputs two control signals to control directly and drive switching actions of two electronic switches of a half-bridge-type circuit architecture. The half-bridge-type control signal generating circuit comprises an AND-gate logic unit, a NAND-gate logic unit, a circuit protection unit, a function generator, a clock generator, a soft boot unit connected to the clock generator, a sample and hold unit, a first comparator connected to the soft boot unit and the function generator, an OR-gate logic unit connected to the soft boot unit, the first comparator, the AND-gate logic unit and the NAND-gate logic unit, a second comparator connected to the sample and hold unit, the function generator, the AND-gate logic unit and the NAND-gate logic unit, and a dead time control unit connected to the function generator, the AND-gate logic unit and the NAND-gate logic unit.

Abstract: A switching power supply apparatus (200) for controlling the operation of a switching FET (225) adapted for switching a rectified smoothed output of a primary side rectifying smoothing circuit (215) by a switching controlling circuit (230) having a hysteresis low-voltage mistaken operation prohibiting circuit. An output of a ternary winding (220C) of a converter transformer is rectified and smoothed by a rectifying smoothing circuit (238) to drive the switching controlling circuit (230). An output voltage of the ternary winding (220C), varied in dependence upon the load state on the secondary side of a converter transformer (220) is set so as to be lower than a low voltage protective voltage in case the voltage is lower than a design load and so as to be higher than the low voltage protective voltage in case the voltage is higher than the design load, in order to carry out an intermittent operation during standby time.

Abstract: The present invention is directed to a switching power supply apparatus (100) adapted for controlling switching operation of a switching FET (125) which carries out switching of rectified and smoothed output of a primary side rectifying/smoothing circuit (115) by a switching control circuit (130) including a hysteresis low voltage malfunction preventing circuit, wherein lowering time until rated voltage at which constant voltage by self-discharge can be maintained is caused to be longer than time until operating voltage of the low voltage malfunction preventing circuit of the switching control circuit of the primary side at the time of no load, and lowering time until rated voltage at which constant voltage by self-discharge can be maintained is caused to be shorter than time until operating voltage of the voltage malfunction preventing circuit at the time of ordinary load to thereby suppress power consumption as minimum as possible to realize energy-saving at the time of standby.

Abstract: 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.

Abstract: A voltage converter including a transformer having a primary winding connected in series with a switch for cutting-up a supply voltage and having a secondary winding associated with a capacitor providing a D.C. low voltage, and a self-oscillating control circuit of the switch for detecting the end of the demagnetization of an auxiliary winding of the transformer, to turn the switch on, and for detecting the current in the on-state switch to turn it off when this current reaches a reference point. The reference point is made variable according to the voltage across the auxiliary winding.

Abstract: A switching power supply apparatus (200) for controlling the operation of a switching FET (225) adapted for switching a rectified smoothed output of a primary side rectifying smoothing circuit (215) by a switching controlling circuit (230) having a hysteresis low-voltage mistaken operation prohibiting circuit. An output of a ternary winding (220C) of a converter transformer is rectified and smoothed by a rectifying smoothing circuit (238) to drive the switching controlling circuit (230). An output voltage of the ternary winding (220C), varied in dependence upon the load state on the secondary side of a converter transformer (220) is set so as to be lower than a low voltage protective voltage in case the voltage is lower than a design load and so as to be higher than the low voltage protective voltage in case the voltage is higher than the design load, in order to carry out an intermittent operation during standby time.

Abstract: This switching circuit includes a transformer having primary and secondary windings insulated from each other; a voltage-driven switching element which is connected in series to one of the primary and secondary windings and has a control terminal for controlling a switching operation thereof; a drive circuit which has an output connected to the control terminal and drives the main switching element; and an auxiliary winding which is provided in parallel to the primary winding of the transformer and has an output connected to the control terminal via a capacitor with positive feedback.

Abstract: A DC-DC converter includes an ON-timing delay circuit in which, when an ON signal is output from a power switch driving circuit in a control IC to a power switch, the ON timing of the power switch is delayed by hindering the start of the ON operation of the power switch. An early turnoff circuit is provided in which, during delay of the ON timing of the power switch, a commutating synchronous rectifier has an ON and OFF switching operation that is inverse with respect to that of the power switch. A delay eliminating circuit is provided which promptly stops the delay operation of the ON-timing delay circuit when detecting the turnoff of the commutating synchronous rectifier which is caused by a drop in the gate of a commutating synchronous rectifier. When the delay operation of the ON-timing delay circuit continues after the turnoff the commutating synchronous rectifier, a loss caused by the continuation of the delay operation occurs. The problem can be prevented by the delay eliminating circuit.

Abstract: A fluorescent lamp lighting apparatus in accordance with the present invention has first switching means (M1) driven by a high-voltage-side pulse signal input from a drive-signal generation circuit and second switching means (M2) driven by a low-voltage-side pulse signal input from the drive-signal generation circuit, wherein the first switching means (M1) is connected in series with the second switching means (M2), and a first capacity (C5) and an inductance element (L1) and the above-mentioned second switching means (M2) are provided between the high-voltage-side terminals of a pair of filament electrodes of a light-emitting tube (4), whereby a constant luminous flux can be maintained immediately after lighting.