Abstract: A method of operating a resonant power converter(1, 2), having a high side switch(3) and a low side switch(4), is disclosed in which the switching is controlled to allow for improved operation at low power levels. The method involved an interruption to the part of the switching cycle in which the low side switch (4) is normally closed, by opening the switch at a particular moment in the cycle which allows the energy to be store in the resonance capacitor (5). Since, as a result, the energy is largely not resonating but stored in a single component, the time quantization of the mode of operation is significantly reduced or eliminated.

Abstract: The invention discloses a control circuit for an AC-DC converter. The control circuit includes a power control circuit for comparing an input current sensing signal generated by sensing an input current of the AC-DC converter and a power level control input and in response thereto generating a frequency modulation control signal, in which the frequency modulation control signal is used to control the output power of the AC-DC converter and suppress harmonics of the input current, and a square wave generator connected to the power control circuit for generating a driving signal used to drive the switch circuit of the AC-DC converter according to the frequency modulation control signal, in which the frequency of the driving signal is varied with the frequency modulation control signal, thereby suppressing harmonics of the input current and regulating the switching frequency the AC-DC converter, and regulating the output power of the AC-DC converter.

Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: A power supply converting circuit includes a multi-phase pulse-width modulation (PWM) controller, a single-phase PWM controller, some first voltage converting circuits, a second voltage converting circuit, and an electrical switch unit. The multi-phase PWM controller provides some first PWM signals and a second PWM signal. The single-phase PWM controller provides a third PWM signal. The first voltage converting circuits receive the first PWM signals to output a first power supply to a central processing unit (CPU) chipset. The electrical switch unit receives the second and third PWM signals to selectively output the second or third PWM signal to the second voltage converting circuit to output one of the first and second power supplies, such that the second voltage converting circuit selectively outputs one of the first and second power supplies to the CPU chipset.

Abstract: An audio power conversion system includes a power supply having a positive supply rail and a negative supply rail for supplying power to a single ended class D amplifier. The system further includes a supply pump reduction circuit connected to the supply rails and adapted to redistribute a pumping charge from said power supply by forcing a current-flow from a rail with a higher voltage to a rail with a lower voltage. According to the at least one embodiment of the invention, the redistribution circuit is arranges to always distribute charge from the rail with the higher voltage. Thus, for practical circuits, the pump canceling occurs continuously and is not confined to every other cycle.

Abstract: The frequency characteristic of a voltage-feedback class-D amplifier circuit for driving an output load is improved. A triangular-wave correction circuit which compensates a gradient of a triangular wave is provided to a triangular-wave signal generator which supplies a triangular wave signal used as a PWM carrier to a comparison circuit for performing PWM modulation of an input signal. In an area where a duty of a command value for an output circuit drive becomes about 50%, a slew rate (gradient) of the triangular wave is decreased.

Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: An inductive power transfer system for coupling a power source to a load across an air gap is provided, including a primary unit and a secondary unit separable from the primary unit and arranged to receive power inductively from the primary unit when placed proximate thereto. The system includes a multi stage comparator for monitoring operating conditions within the secondary unit and feedback loop for transmitting a feedback signal to the primary unit when predetermined operating conditions are detected within the secondary unit. The primary unit is arranged to operate in a low power mode where power is applied to the primary winding for a minimal period during each switching cycle when no feedback signal is received and a high power mode where power is applied to the primary winding for the majority of each switching cycle when a feedback signal is received.

Abstract: A power supply system allowing remote adjustments of the power output of the power supply unit without having to physically access the power supply unit itself is disclosed. A power supply system in accordance with the present invention utilizes a central processing unit (CPU) to provide a command that adjusts to the power output via a modified pulse width modulator (MPWM). Moreover, the central processing unit (CPU) may also be used to provide fine tune adjustments to the error signal of the power supply system, wherein the central processing unit (CPU) produces a command for the modified pulse width modulator to control the power output.

Abstract: A switching power supply exhibits high conversion efficiency and facilitates reducing the size thereof. The switching power supply includes a half-bridge circuit including a first series circuit formed of switching devices Q1 and Q2 and connected between the output terminals of a DC power supply; and a second series circuit connecting primary inductance Lr1 of transformer T1, primary inductance Lr2 of transformer T2 and capacitor Cr in series. The second series circuit is connected between the output terminals of the half-bridge circuit, and is made to conduct a series resonance operation. The switching devices Q1 and Q2 is controlled at the ON-duties of 0.5 for reducing the breakdown voltages of rectifying diodes D1 and D2 on the secondary side of transformers T1 and T2 and for improving the conversion efficiency of the switching device.

Abstract: A switching controller for power converter comprises a current-sense circuit and a PWM circuit, The current-sense circuit receives high-voltage signal across a first switch to generate a current-sense signal. The PWM circuit generates a switching signal to control the first switch in response to the current-sense signal. The switching controller further comprises a delay circuit. The delay circuit receives the switching signal to generate a delayed switching signal. The current-sense signal and the high-voltage signal ramp up with the same slope during the delayed switching signal is enabled. The current-sense signal will be pulled down to a level of a ground reference during the delayed switching signal is disabled. A delay time provided by the delay circuit avoids the high-voltage signal at the instance which the first switch is being turned off being conducted to a first comparator and a second comparator via a second switch.

Abstract: A control device for a resonant converter, the control device including a first circuit to integrate at least one signal indicating a half wave of a current circulating in a primary winding of a transformer; the first circuit is structured to generate at least a control signal of the switching circuit depending on the integrated signal. The control device includes a second circuit to impose the equality of a switching-on time period of the first and second switches.

Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: A switched mode converter is disclosed that includes mode logic for switching between voltage mode and current mode. The converter includes sensing circuitry for sensing current on the primary side, load current on the secondary side, and converter output voltage. When load current is less than a predetermined value, the converter operates in voltage mode wherein output voltage of the voltage mode controller is used to control the duty cycle of a PWM controller. When load current is greater than a predetermined value, the converter operates in current mode wherein primary current is used to control the PWM controller. Thus during a light load when the converter is voltage controlled there is no need for a minimum load to stabilize the control loop. In current-mode the control loop will have faster transient response and avoid flux imbalance. Thereby providing advantages of both voltage and current controlled switched mode converters.

Abstract: A stepping motor driving device drives a stepping motor according to a drive pulse of a step signal. A phase matching unit matches, at a time when there is a possibility that a rotor and a phase signal are out of phase with each other, phases of the rotor and the phase signal by applying at least one drive pulse after energizing the stepping motor for a predetermined time and applying a phase signal having a predetermined duration for a final pulse.

Abstract: A dual mode modulator is proposed for driving a power output stage having a serial connection of high-side power FET and low-side power FET. The dual mode modulator includes a PWM modulator operating under a PWM-frequency and a PFM modulator for controlling the power output stage. To improve the dynamic load regulation of the dual mode modulator, a dynamic frequency booster can be added to the dual mode modulator to boost up the PWM-frequency from its normal operating frequency during a PFM-to-PWM mode transition period. Secondly, a dynamic slew rate booster can be added to boost up an error amplifier slew rate of the PWM modulator from its normal operating slew rate during the mode transition period. Thirdly, a dynamic turn-off logic circuit can be added to turn off the low-side power FET during the mode transition period.

Abstract: A DC power source voltage is supplied to a center tap of a primary winding, and first and second semiconductor switches alternately turned on are disposed between each of both ends of the primary winding and a common potential point, and a current flowing through a load is fed back and PWM control of each of the semiconductor switches is performed. Also, snubber circuits are respectively connected between a ground and the center tap of the primary winding, and an abnormal high voltage at the time of switching is reduced. Also, a parallel running of plural inverters is simply performed by disposing PWM comparators corresponding to the first and second semiconductor switches.

Abstract: A power transistor chip with built-in enhancement mode metal oxide semiconductor field effect transistor and application circuit thereof provides an enhancement mode metal oxide semiconductor field effect transistor in association with two series connected resistors to act as a start-up circuit for the AC/DC voltage converter. The start-up circuit can be shut off after the pulse width modulation circuit of the AC/DC voltage converter circuit works normally and still capable of offering a function of brown out detection for the pulse width modulation circuit as well. Besides, the enhancement mode metal oxide semiconductor field effect transistor is built in the power transistor chip without additional masks and processes during the power transistor chip being fabricated such that the entire manufacturing process is simplified substantively with the economical production cost.

Abstract: An exemplary inverter circuit (200) includes a direct current (DC) input terminal (210); a transformer (230) including a first primary winding (231) and a second primary winding (232); a first switch transistor (240); a second switch transistor (250); a pulse generator (260) providing pulse driving signals to the first switch transistor and the second transistor respectively; and a resistor (29). The first primary winding and the second primary winding share a tap (235), the tap is connected to the DC input terminal via the resistor. A drain electrode of the first switch transistor is connected to the tap via the first primary winding, and a drain electrode of the second switch transistor is connected to the tap via the second primary winding.

Abstract: Dead time compensated complementary pulse width modulation (PWM) signals are derived from a PWM generator by first applying time period compensation to the PWM generator signal based upon the direction of current flow in an inductive load being controlled by the PWM generator. Dead time is then applied to the compensated PWM generator signal for producing complementary dead time compensated PWM signals for controlling power switching circuits driving the inductive load.

Abstract: A power converter for converting an input voltage (Vin) into an output voltage (Vout), comprising a first supply potential and a second supply potential established by the input voltage, and at least one primary winding having two terminals, a center tap arranged between the two terminals and connected to the first supply potential, and at least one secondary winding magnetically coupled to the primary winding for providing at least one output voltage (Vout) and a first controllable switch connected between the second supply potential and one terminal of the primary winding and a second controllable switch connected between the second supply potential and the other terminal of the primary winding and a third controllable switch connected between the second supply potential and the one terminal of the primary winding and a fourth controllable switch connected between the second supply potential and the other terminal of the primary winding, and a control unit for controlling the switches such that the first, s

Abstract: A dual-switch forward power converter, and a method of operating the same, employs a self-coupled driver to achieve among other advantages higher efficiency, lower part count and component cost. In one aspect of the present invention, a power converter comprises a transformer and two switching transistors, and said transformer has two serially-connected primary windings with the first winding connected to a first switching transistor which is biased by a pulse controller, and the second winding couples the voltage across said first winding to bias the second switching transistor. In addition, the circuit on the primary side of said transformer further comprises means of dissipating magnetization current and the circuit on the secondary side comprises a rectifier and a low-pass filter.

Abstract: AC/DC power converters having an under voltage lockout circuit with first and second thresholds and associated methods of operation are disclosed herein. In one embodiment, the first threshold is greater than the second threshold. The under voltage lockout circuit is configured to enable a current source to charge the capacitor when the voltage across the capacitor is less than the second threshold. The under voltage lockout circuit is configured to shut off the current source and to enable a pulse width modulator circuit to switch a transistor when the voltage is greater than the first threshold.

Abstract: A switched mode converter is disclosed that includes mode logic for switching between a voltage mode and a current mode. The converter includes circuitry for sensing current on the primary side of the transformer, load current on the secondary side, and output voltage. When the load current is less than a predetermined value, the output voltage of the voltage mode controller is used to control the duty cycle of a PWM controller. When the load current is greater than a predetermined value, the primary current is used to control the PWM controller. During a light load the converter is voltage controlled and there is no minimum load needed to stabilize the control loop. In a current-mode, the control loop will have a relatively faster transient response and avoid flux imbalance in push-pull topology. The converter provides the advantages of both known voltage controlled and current controlled switched mode converters.

Abstract: The rising edge of a pulse width modulated output signal occurs after an input ramp signal starts to rise. The ramp signal starts to rise after the rising edge of a periodic set signal and before the falling edge of a periodic set signal. A feedback control signal intersects a substantially linear region of the ramp signal to generate a reset signal using a PWM comparator. The periodic set signal and reset signal are input to a latching circuit to generate the pulse width modulated output signal. The minimum pulse width can approach zero while having adequate overdrive to the PWM comparator. Having the rising edge of the reset signal rise before the falling edge of the set signal can allow a zero percent duty cycle without the need for a ramp offset voltage.

Abstract: A method is proposed for supplying electrical power to a DC motor (16) which can be commutated electronically via a semiconductor power output stage (28), preferably a three-phase DC motor, through which a control unit (22) passes current in blocks, corresponding to the signals from a rotor position sensor (20). Current is passed through the motor (16) variably in steps, in such a manner that the magnitude and/or the duration and/or the trigger angle of the current blocks can be varied as a function of the rotation speed and/or of the load, with respect to the profile of the induced voltage (E).

Abstract: A power converter according to the present invention comprises a resonant tank. The resonant tank is switched by a plurality of transistors. A control circuit generates a plurality of switching signals to control the transistors. The pulse widths of the switching signals are modulated for regulating an output voltage of the power converter. The control circuit is coupled to detect an input voltage of the power converter. The frequency of the switching signals is changed in response to the change of the input voltage or/and an output load of the power converter.

Abstract: Disclosed is an apparatus and method for driving a 2-phase SRM capable of individually performing an initial driving by an initializing sensor and a normal driving by a driving sensor, and capable of controlling a rotation speed of the SRM by delaying a phase signal by a half period and then generating a pulse width modulation signal based on the period. The apparatus comprises: a driving sensor which detects a position of a rotor thus to generate a driving sensor signal based on a result of the detection; a microprocessor which generates a 1-phase signal and a 2-phase signal based on a rising time and a falling time of the driving sensor signal at the time of a normal driving; an oscillator which generates first and second pulse width modulation signals delayed by a preset time; and a multiplying unit which multiplies the 1-phase and 2-phase signals with the first and second pulse width modulation signals, and generates 1-phase and 2-phase driving signals based on a result of the multiplication.

Abstract: A bidirectional active power conditioner includes a DC side, a bidirectional DC/DC power converter, a DC/AC inverter and an AC side. The DC side electrically connects with a DC source while the AC side electrically connects with a load and an AC source. The bidirectional DC/DC power converter is controlled via high-frequency pulse width modulation (PWM) switching so as to generate a predetermined DC voltage or DC current while the DC/AC inverter is controlled to convert the predetermined DC voltage or DC current into a predetermined AC voltage or AC current.

Abstract: A system for generating and monitoring voltages on a variety of different components on a common printed circuit board. The system includes a programmable controller, a plurality of DC/DC converters for producing voltages for the devices and a plurality of voltage regulators for produced voltages for a plurality of CPUs on the board, such CPU voltages being produced in accordance with VIDs provided to the regulator by the CPU. The programmable controller: establishes a set point voltage for such one of the DC/DC converters; sequentially monitors the produced voltages produced, monitors voltages produced by the regulators for the CPUs by comparing the VIDs to the voltages produced by the regulators, and if during the sequencing any one of the converters is determined by the programmable controller as producing an improper voltage or if the any one of the regulators fails top produce the voltage indicated by the VIDs, disables the board.

Abstract: A resonant switching power converter having burst mode transitioning operates during low or zero load conditions with reduced audible noise and component stresses, while improving efficiency. Pulse bursts are generated with a beginning and/or ending pulse duration that differs from mid-burst pulse durations, in order to reduce an amplitude of transients otherwise generated at the beginning and/or end of the bursts. Alternatively, the spacing between the pulses at the beginning and/or end of the bursts may differ from the spacing between the pulses in the middle of the bursts to reduce the transient(s). A number of pulses at the beginning and/or end of the burst can also be set with gradually varying durations, to further reduce component stress and audible vibration in a transformer that couples the resonant tank to the output of the converter.

Abstract: A digital timing read back and an adaptive feedforward compensation algorithm to reduce harmonic distortion is disclosed. More specifically, the approach generates harmonic components digitally with the same magnitude but at an opposite phase to the output harmonic distortion. An anti-distortion signal is generated and added to the input signal. The magnitude and phase of the harmonic distortion change with the modulation level or index and the frequency of the input signal. In addition, the harmonic distortion level varies significantly with different timing error statistics in different power devices. The inventive method takes the modulation level or index, the frequency of the input signal and the timing error statistics acquired through a digital read back circuit as input variables to determine the magnitude and phase of the anti-distortion signal.

Abstract: First and second semiconductor switches which are activated alternately are provided between ends of a primary winding and a common potential point, wherein a DC power supply voltage is supplied to a center tap. An electric current flowing into a load is fed back to thereby subject the semiconductor switches to PWM control. Series circuits consisting of capacitors and semiconductor switches are connected between the center tap of the primary winding and the ends of the same. The semiconductor switches are activated in synchronism with the first and second semiconductor switches, thereby preventing occurrence of an anomalous high voltage, which would otherwise be caused at the time of switching operation.

Abstract: A half bridge converter having a pulse width control unit, a level regulating unit, a half bridge switch unit, an electricity converting unit and a feedback unit is disclosed. The level regulating unit receives a first DC electricity and boosting the first DC electricity to a working voltage level for forming a working electricity. The pulse width control unit produces a conduction cycle signal for controlling the half bridge switch unit to switch the working electricity to a conduction timing of the electricity converting unit, so that the electricity converting unit converts the working electricity to output a second DC electricity. The feedback unit draws a feedback signal from the second DC electricity to send to the level regulating unit for altering the voltage of the working electricity, so as to adjust the output of the electricity converting unit, thereby achieving voltage regulation.

Abstract: A DC power source voltage is supplied to a center tap of a primary winding, and first and second semiconductor switches alternately turned on are disposed between each of both ends of the primary winding and a common potential point, and a current flowing through a load is fed back and PWM control of each of the semiconductor switches is performed. Also, snubber circuits are respectively connected between a ground and the center tap of the primary winding, and an abnormal high voltage at the time of switching is reduced. Also, a parallel running of plural inverters is simply performed by disposing PWM comparators corresponding to the first and second semiconductor switches.

Abstract: A switched mode converter is disclosed that includes both voltage mode and current mode control. The switched mode converter also includes mode logic for switching between a voltage mode and a current mode. The converter includes current sensing circuitry for sensing the switcher current on the primary side of the transformer and the load current on the secondary side as well as voltage sensing circuitry for sensing the converter output voltage. When the load current is less than a predetermined value, the converter operates in a voltage mode. During the voltage mode, the output voltage of the voltage mode controller is used to control the duty cycle of a pulse width modulation (PWM) controller. When the load current is greater than a predetermined value, the converter operates in a current mode. In a current mode, the primary switcher current is used to control the PWM controller.

Abstract: According to one embodiment, a voltage regulator includes a switch configured to selectively conduct electrical energy according to a signal, and circuitry configured to provide the signal to implement a soft start procedure comprising varying frequency and duty cycle of the signal.

Abstract: Conduction loss in the body-diode of a low side MOSFET of a power switching stage of one phase of a coupled-inductor, multi-phase DC-DC converter circuit, associated with current flow in the output inductor of that one phase that is induced by current flow in a mutually coupled output inductor of another phase, during normal switching of that other stage, is effectively prevented by applying auxiliary MOSFET turn-on signals, that coincide with the duration of the induced current, to that low side MOSFET, so that the induced current will flow through the turned-on low side MOSFET itself, thereby by-passing its body-diode.

Abstract: According to prior art, a clock frequency increase for clocked high-frequency integrated circuits, in particular microprocessors, reaches a current physical limit of approximately 3 GHz, as dynamic current modifications cannot be sufficiently compensated. The aim of the invention is to provide a power supply for electronic systems with a double-figure GHz range. To permit the rapid compensation of dynamic current modifications, the current compensation circuit (10) is placed in the vicinity of the integrated circuit (11) or is integrated into the latter. A control amplifier (8) influences a pulsewidth modulator (2) by means of an optical coupler (9). Said pulsewidth modulator control controls a normal mode voltage converter (3, 4) with synchronous rectification (5). A specific application area for the invention is the supply of future high-performance microprocessors, whose development has been delayed by the aforementioned power problem.

Abstract: A boost switching converter with multiple outputs includes an inductor is connected between an input supply (typically a battery) and a node Vx. A low-side switch connects the node Vx and ground. Two or more output stages are included. Each output stage includes a high-side switch and an output capacitor. Each output stage is connected to deliver electrical current to a respective load. A control circuit is connected to drive the low-side switch and high-side switches in a repeating sequence. The inductor is first charged and then discharged into each output stage. In effect, a series of different switching converters are provided, each with a different output voltage.

Abstract: A DC/DC converter includes an input filter, a half-bridge converter without PWM (Pulse Width Modulation) control function, a synchronous rectifier, an output capacitor, and a DC transformer. The DC transformer includes a magnetic core, a primary winding, a first secondary winding, and a second secondary winding. The magnetic core of the DC transformer includes a first leg, a second leg having a first air gap, and a third leg having a second air gap. The first secondary winding is wound on the first leg and the second leg, and induces a first inductance by the first air gap. The second secondary winding is wound on the first leg and the third leg, and induces a second inductance by the second air gap.

Abstract: A high-voltage power supply (10) includes: a power scaling section (130) that receives an input voltage signal and converts the input voltage signal to a controllable DC voltage; a push-pull converter (140) for converting the controllable DC voltage to a high-frequency wave; and a voltage multiplier (200) receiving the high-frequency wave generated by the push-pull converter (140) and performing successive voltage doubling operations to generate a high-voltage DC output. In one implementation, the voltage multiplier (200) receives a square wave having a frequency of approximately 100 kHz and outputs an adjustable DC voltage of approximately 0-to-30 kV. In one implementation, the high-voltage power supply (10) includes an insulation system (250) for the voltage multiplier module (200), such an insulation system being formed of n insulating layers and m conducting strips positioned between successive insulating layers.

Abstract: A bidirectional DC to DC converter having a first operational mode and a second operational mode includes a first terminal pair that has a positive terminal and a negative terminal and that connects the converter to a first electric circuit, a second terminal pair that has a positive terminal and a negative terminal and that connects the converter to a second electric circuit, an accumulation element for temporary accumulation of electric energy; and a switching circuit connected to the first terminal pair, the second terminal pair, and the accumulation element. Electric energy is transferred from the first electric circuit to the second electric circuit via the accumulation element in the first operational mode of the bidirectional DC to DC converter and, from the second electric circuit to the first electric circuit via the accumulation element in the second operational mode of the DC to DC converter.

Abstract: A signal converting apparatus is disclosed and includes a swing range converting unit converting an error signal swinging in a first swing range to an adjusted error signal swinging in a second swing range, an oscillator generating a periodic oscillation signal swinging in approximately the second swing range, and a comparator receiving and comparing the adjusted error signal and the oscillation signal, and generating a pulse-width modulated signal in relation to the comparison.

Abstract: Methods and apparatus to control a digital power supply are disclosed. An example method includes controlling a power factor controller by: receiving a first current signal flowing in a first stage of the power factor controller, receiving a second current signal flowing in a second stage of the power factor controller, determining a difference between the first current signal and the second current signal, determining if the magnitude of a measured current signal is above a predetermined threshold, activating an integrator to integrate the difference when the magnitude of the measured current signal is above a predetermined threshold, and outputting a first control signal and a second control signal to the power factor controller based on the output of the integrator.

Abstract: A full bridge inverter includes a push/pull control chip outputting a first control signal and a second control signal. Each duty cycle of the two control signals is smaller than 50%. Moreover, both a first driver and a second driver are coupled to the push/pull control chip and a DC power. A full bridge switch assembly with four N-MOSes couples to the DC power, the first driver, the second driver and a transformer, and converts the DC power into an AC power by the first driver and the second driver. The AC power is transmitted to a first side of the transformer.

Abstract: A bi-directional switch for a power converter comprises first and second transistors (SW1, SW2) and a floating supply capacitor (C2) associated with the second transistor (SW2). The drive circuit and/or gate of the first transistor (SW1) is charged by the floating supply capacitor (C2) of the second transistor (SW2). The charging takes place at a predetermined moment in the switching cycle, and in particular at a moment in the switching cycle when the voltage across the bi-directional switch is substantially a minimum.

Abstract: Described is an inverter device suitable for driving a cold cathode fluorescent lamp (CCFL), comprising a transformer having a primary winding and a secondary winding. The primary winding has two terminals connected to a return-path terminal of a direct current (DC) power source through a second switch and a third switch, respectively, and a center tap connected to an output of the DC power source through a first switch. A signal controlling unit is further included to control the switches in such a manner that the second and third switches are on concurrently or alternatively in cooperation with the first switch. As such, an alternating current (AC) power is fed to the primary winding of the transformer and an output of the transformer is supplied to the CCFL.