Abstract: A DC-AC converter has two half-bridge circuits using an input feedback signal and an input clock signal together with time delay circuits, wherein one of the half-bridge circuits drives one pair of corresponding FETs and the other half-bridge circuit drives the other pair of corresponding FETs. The DC-AC converter includes: a Direct Current (DC) power source; a switching unit which includes a plurality of Field Effect Transistors (FETs) for changing paths of Direct Current (DC), so as to convert the DC to Alternating Current (AC); a transformer for transforming a voltage input from the switching unit; a load unit connected to the transformer; and a signal control unit for simultaneous parallel control of the FETs in the switching unit.

Abstract: A DC-AC converter has two half-bridge circuits using an input feedback signal and an input clock signal together with time delay circuits, wherein one of the half-bridge circuits drives one pair of corresponding FETs and the other half-bridge circuit drives the other pair of corresponding FETs. The DC-AC converter includes: a Direct Current (DC) power source; a switching unit which includes a plurality of Field Effect Transistors (FETs) for changing paths of Direct Current (DC), so as to convert the DC to Alternating Current (AC); a transformer for transforming a voltage input from the switching unit; a load unit connected to the transformer; and a signal control unit for simultaneously parallel control of the FETs in the switching unit.

Abstract: An electronic ballast for use in illuminating a lamp includes a voltage reference generator that uses a plurality of current amplifiers and resistors having substantially identical resistance characteristics to remain stable in response to temperature variations and despite resistance process dispersion. The reference voltage generator further includes an ON/OFF controller and a dimming function that may be controlled via a single input terminal. Additionally, the dimming function uses a capacitor to prevent abrupt changes in an input signal from causing abrupt changes in a feedback signal that controls an output frequency of the ballast.

Abstract: An electronic ballast for use in illuminating a lamp includes a lamp driving circuit having a pulse-width modulated signal generator, a timing capacitor coupled to the lamp driving circuit, and a power controller. The power controller uses a current sense resistor to detect a current flowing through the lamp and an operational amplifier circuit to compare a signal associated with the detected current to a reference voltage associated with a desired lamp current. Based on the comparison, the power controller provides a correction current to the timing capacitor to control a duty cycle of an output of the pulse-width modulated signal generator.

Abstract: Disclosed is an electric ballast system.

Abstract: A Power Factor Correction (PFC) circuit according to the present invention includes a boost converter which outputs a predetermined voltage according to control of a switch. The switch is coupled to a resistor and a capacitor which, by forming a current detector, detect the current flowing through an inductor of the boost converter. The output voltage of the boost converter is divided by resistors, and the voltage difference between the divided voltage and a reference voltage is amplified by an error amplifier. The output voltage of the error amplifier and a reverse sawtooth waveform provided from an oscillator are input in a multiplier so as to be multiplied by a gain, and output voltages of the multiplier and of the current detector are provided to a switching driver. The switching driver turns off the switch when the output voltages of the current detector and of the multiplier are equal, and turns on the switch when the state of the reference clock signal is changed.

Abstract: Disclosed is a Power Factor Correction (PFC) controller which comprises a boost converter, an error amplification unit, a calculator, and a switching driver. The error amplification unit reduces the error voltage of the output voltage of the boost converter to a specific reference voltage. The calculator receives first and second input voltages proportional to the input power of the converter and the output voltage of the error amplification unit, and outputs the voltage proportional to the first input voltage and the output voltage of the error amplification unit and inversely proportional to the second input voltage. The switching driver controls the switch to OFF when the voltage which detects the current flowing to switch of the boost converter becomes equal to the output voltage of the calculator, and controls the switch to ON when the zero current of the coil of the boost converter is detected.

Abstract: A pulse width modulation controller is shown which includes an error amplifier, a multiplying portion, an oscillator, a comparator, a flop-flop and a logic gate. The error amplifier receives an externally input feedback voltage and a first reference voltage in order to compare each voltage, and, in a current mode, the multiplying portion outputs a voltage which is proportional to the multiplication product of a voltage generated from a power switching unit and the difference between a second reference voltage and a voltage output from the error amplifier, and, in a voltage mode, outputs a voltage which is proportional to the multiplication product of a ground voltage and the difference between the second reference voltage and the voltage output from the error amplifier. The oscillator generates a clock signal and an inverse sawtooth signal. The comparator compares the inverse sawtooth signal with the output voltage of the multiplying portion.

Abstract: A sequential feedback control system for an electronic ballast provides feedback control during soft start and dimming operations. The system includes a feedback control portion that generates a feedback signal responsive to the power consumption of the ballast and receives a control signal for controlling the power consumption of the ballast. A dimming controller generates a dimming signal responsive to a time signal, and a soft start controller generates a soft start signal responsive to the time signal. An adder generates the control signal by adding the feedback signal and the dimming signal. The dimming controller includes a first resistor for setting the steady state power level during dimming operations and a second resistor for setting the rate of change of the power level.

Abstract: A power factor correction circuit for a boost converter includes a current feedforward loop that senses the input voltage by detecting variations in the rate of change of current in an inductor, thereby eliminating the need for a voltage feedforward loop. A current sense circuit generates a current signal responsive to the input current flowing through the inductor when a switching transistor is turned on. A comparator compares the current signal to a sawtooth signal, thereby generating a control signal for turning the transistor off. The output of the converter is controlled by a voltage feedback loop which includes an error amplifier that generates an error signal responsive to the output voltage. The error signal is then multiplied by the current signal before the current signal is compared to the sawtooth signal.

Abstract: The present invention relates to a feedback control system and method for controlling an electronic ballast for driving a lamp where the lamp requires preheating of a cathode of the lamp in order for the electronic ballast to successfully discharge into the lamp and initiate arcing operation in the lamp. The system detects the power consumption level of the lamp and, when the power consumption level indicates that the lamp is not arcing, performs a restart of the lamp wherein the restart function includes preheating the cathode with a preheating current. The present invention reduces production cost and increases safety by detecting operation in the lamp without using external elements.

Abstract: A power factor correction circuit for a boost-type voltage converter determines the input voltage by sensing the rate at which the current through an inductor changes when a switching transistor is turned on. The circuit includes a current sense circuit which generates a control signal in response to the current flowing in the inductor. The control signal is compared with a sawtooth signal to control the input current waveform. An output detecting circuit generates a comparison reference signal for regulating the output voltage of the converter. The comparison reference signal is summed with the control signal to provide a comparison signal. A comparison circuit compares the comparison signal with the sawtooth signal and generates a pulse width modulated signal for controlling the switch. A compensation signal generator generates a compensated comparison signal in response to a ripple component in the output signal of the converter.

Abstract: A feedback control system for electronic ballast comprises a lamp, an electronic ballast, a multiplier, a time controller, a first adder-subtracter, a reference voltage generator, a second adder-subtracter, an error amplifier, a capacitor, a voltage controlled current source VCCS, a third adder-subtracter and an oscilloscope and output driver.

Abstract: A controller for performing a zero voltage switching using a resonance mode converter, and an electronic ballast adopting the same, includes a power controller, a shutdown protection circuit and a brownout circuit, and performs a switching when voltage of a switching element is zero, thereby preventing excessive power consumption, enhancing efficiency and decreasing noise.

Abstract: A feedback dimming control circuit for controlling the luminance of a plurality of lamps, the circuit comprising: a multiplier receiving and multiplying a feedback current and an input voltage, a first subtracter generating an error signal by subtracting an output voltage from the multiplier from a reference voltage, a second subtracter subtracting a signal responsive to the error signal from the input voltage, an oscillator generating a periodic signal in response to the output of the second subtracter; and a tank resonating in response to the periodic signal and generating the feedback current.

Abstract: Switching loss in push-pull switching transistors in a resonant inverter or the like, is minimized by assuring the switching of each of the transistors into conduction occurs when the voltage across its principal conduction path is zero-valued, or substantially so. This is done responsive to sensing the flow of forward currents through clamp diodes connected across the principal conduction paths of each of the transistors. This sensing is done so as to avoid the need for an additional coupling transformer. More particularly, the current flow to or from either of the terminals of the primary direct voltage supply, which current flow is in a first direction when either of the switching transistors is conductive and is in a second direction opposite to the first direction when the clamp diodes are conductive, is sensed for determining the times when the switching transistors are to begin to be conditioned for conduction.

Abstract: A power factor correction circuit in which an inductor current is detected separately as a charging current indication signal and a discharging current indication signal by using a current sense resistor and a current sense circuit. A scaled-down output DC voltage is compared with a predetermined reference DC voltage by using an error amplifier which serves to produce an output voltage error signal. The output voltage error signal is then multiplied with a divided-down rectified input line voltage through the use of the multiplier to generate a sinusoidal reference signal. The sinusoidal reference signal is used by peak and valley comparators which also receive the charging and the discharging current indication signals. The outputs from the peak and the valley comparators are used to control a FET transistor which controls the input line current. As a result, the power factor correction circuit is capable of effectively eliminating a dead time and thereby achieving a near unity power factor.

Abstract: A controller for performing a zero voltage switching using a resonance mode converter, and an electronic ballast adopting the same, includes a power controller, a shutdown protection circuit and a brownout circuit, and performs a switching when voltage of a switching element is zero, thereby preventing excessive power consumption, enhancing efficiency and decreasing noise.

Abstract: A zero-voltage switching type electronic ballast for a fluorescent lamp includes a pair of capacitors connected in series between first and second nodes of a DC power source; a pair of switching devices whose current passages are connected in series between the first and second nodes of the DC power source; a load resonant circuit portion having a serial resonant circuit between the connection node of the pair of capacitors and the connection node of the pair of switching devices, and a discharge lamp; capacitors each connected in parallel to the current passage of the switching devices; a driving transformer having a secondary side which includes first and second windings each connected to the respective switching devices and having opposite polarities, and a third winding having the same polarity as the first winding and connected between the connection node of the pair of switching devices and the load resonant circuit, and a primary side having a fourth winding to which a switching control signal of a pre