Abstract: A circuit arrangement for supplying a load which comprises a discharge lamp. The circuit includes apparatus for generating a DC voltage and provided with input terminals for connection to a supply voltage source. A rectifier is coupled to the input terminals for rectifying an AC voltage supplied by the supply voltage source. In addition, there are output terminals for connection to the load and a DC-DC converter connected between the rectifier and the output terminals and provided with a first inductor, a first unidirectional element, and a switching element. The output terminals are interconnected by a circuit branch which comprises a series arrangement of an impedance and a first capacitor, which impedance is shunted by a further unidirectional element. As a result, the inrush current which flows immediately after switching-on of the circuit arrangement is limited.

Abstract: In a self-oscillating bridge circuit, the control of the low switch (6) is derived from the control of the high switch (7) by coupling the control circuitry (SC2) of the low switch to a terminal P in the control circuitry of the high switch by means of a diode (D1). The control of the low switch is improved by incorporating control circuitry (SC3) for rendering the low switch conducting for a short period after the high switch has become non-conducting.

Abstract: A circuit arrangement for igniting and operating at least two discharge lamps. the circuit is provided with input terminals (K1,K2) for connection to a supply voltage source and a circuit I (SC, S1, S2) coupled to the input terminals for generating a high-frequency voltage from a supply voltage delivered by the supply voltage source. A load branch B is coupled to the circuit I and comprising a first branch A including first terminals (K3,K3') for accommodating a discharge lamp and a first inductive element L1, and a second branch C shunting the first branch A and comprising further terminals (K4,K4') for accommodating a discharge lamp and a second inductive element L2 which is magnetically coupled to the first inductive element L1. A circuit II limits the voltage across branch A and branch C to a first value during the ignition of the discharge lamps.

Abstract: An integrated circuit control device for driving a half bridge type of inverter. The IC control inverter powers a load including a lamp. The device includes at least one pin, which during the preheat cycle of the lamp is at a high logic level resulting in the coupling of an additional capacitor to an unloaded resonant tank circuit. The overall resonant frequency of the unloaded circuit is reduced making it less likely that a high voltage will be applied to the lamp during preheat. Once the lamp filaments have been preheated the pin is at a low logic level. The low logic level at the pin causes the additional capacitor to be decoupled from the tank circuit. The pin when at the low logic level also receives a signal representing the voltage condition across the lamp.

Abstract: A circuit arrangement for supplying a discharge lamp comprises a control circuit which is provided with an integrated circuit. Means for generating a signal which is a measure of the lamp voltage are coupled to one pin of the integrated circuit. The periodic switching of the integrated circuit between a first and a second state insures that the lamp voltage will not exceed a minimum admissible value and a maximum admissible value. The use of only one pin makes the integrated circuit simple and accordingly inexpensive, while in addition only a small number of external components is required.

Abstract: A circuit arrangement for igniting and operating a discharge lamp (1) comprising inductive means, which include a primary winding (PRIM) which passes a high-frequency current during ignition and during lamp operation, and a secondary winding (SEC) which is magnetically coupled to the primary winding and electrically coupled to an impedance M (C1, C3) for limiting the current passed by the secondary winding. The current through the secondary winding generates a DC voltage via rectifying means, by which current a part of the circuit arrangement is supplied. The circuit arrangement is also provided with apparatus X (R, S1) for increasing the impedance value of the impedance M after ignition of the discharge lamp. The amplitude of the DC voltage is thereby at a desired level both before and after ignition of the discharge lamp, while no major power dissipation takes place during stationary lamp operation.

Abstract: An inverter driving scheme for detecting when an inverter is in or near a capacitive mode of operation. In response to being within a capacitive mode of operation, the switching frequency is immediately increased to its maximum setting. When a near capacitive mode of operation is detected, the switching frequency is increased at a preset rate. During overvoltage conditions across the lamp combined with a near capacitive mode of operation, the switching frequency is immediately increased to its maximum setting.

Abstract: A ballast for powering a lamp at deep dim levels. Driving circuitry includes a feedback loop which compares a desired dim level to a signal representing actual lamp power consumption. The loop is closed once the signal representing actual lamp power consumption equals the desired dim level. During ignition, a switch in response to the lamp voltage reaching or exceeding a predetermined threshold opens the feedback loop. The feedback loop is closed once the lamp has been ignited. By closing the loop as soon as the lamp has been ignited, ignition flash is minimized.

Abstract: A half-bridge driver circuit including a lower drive module and a floating upper drive module for driving respective external upper and lower power transistors of a high voltage half bridge is contained in an integrated circuit chip which includes an on-chip bootstrap diode emulator which is turned on in response to a control signal applied to its gate in order to pass current from a power supply to charge an external bootstrap capacitor that powers the upper drive module. The upper drive module is accommodated in an insulated well and the diode emulator includes as its main current carrying element, a JFET transistor formed along the periphery of the well. The JFET transistor is driven into a conducting state at the same time the lower power transistor is driven into a conducting state.

Abstract: The load circuits for the different lamps of a 2-lamp ballast are selected to have sufficiently different resonant frequencies so that the luminous fluxes of the two are different when the ballast operating frequency is at one of the resonant frequencies. The ballast is operated at a frequency between those two resonant frequencies. The circuit may include a device for measuring the ratio between the luminous fluxes of the two lamps, and the frequency control circuit is then responsive to that ratio.

Abstract: A DC/AC convert circuit for operating a discharge lamp includes a branch A having ends suitable for connection to a DC voltage source and comprising a series circuit of two switching elements for generating a periodic voltage by being conducting and non-conducting alternately at a frequency f, each switching element being shunted by a diode. A control circuit is coupled to control electrodes of the switching elements for rendering the switching elements conducting and non-conducting alternately at the frequency f. A load branch B shunts one of the switching elements and comprises an inductor. The discharge lamp is coupled to the load branch B. The power consumed by the discharge lamp is adjusted by adjusting the value of the difference Tt-Td, in which Tt is a time interval during which one of the switching elements is conducting during a half cycle of the periodic voltage, and Td is the time interval during which a diode is conducting during the same half cycle of the periodic voltage.

Abstract: A semiconductor device is provided having a substrate which includes a floating circuit well with turn on/turn off signals generated by a voltage drop proximate to at least one resistor contained therein, and having high-voltage interconnects to connect the drain terminals of a plurality of LDMOS transistors to the resistor in the floating well and wherein the transistors, resistor and floating well are combined into an integrated structure which eliminates the high voltage interconnect crossovers.

Abstract: The combination of a fluorescent lamp with a grid between its electrodes and control equipment for operating the lamp in an on condition and an off condition by the application of pulses to the grid.

Abstract: A power supply with energy storage means in the form of two capacitors with energy storage means provides improved voltage regulation for the power supply and also serves to store the energy contained in voltage spikes that could otherwise deleteriously effect the power supply.

Abstract: A DC/AC converter (8) having a half bridge circuit for igniting and feeding a gas and/or vapour discharge tube (1). A starting capacitor (94) of this converter is connected between a junction (A) between two branches--each comprising a semiconductor circuit element (60 and 61)--of the half bridge circuit on the one hand and a center tapping (E) of a voltage divider (90, 91) on the other hand. As a result, the converter (8) starts satisfactorily and hence the discharge tube (1) readily ignites, moreover undesired starting pulses during the operating condition are avoided.

Abstract: A DC-AC converter for igniting and supplying a gas discharge lamp (1). The converter has two input terminals (C, D) to be connected to a DC voltage source. The input terminals are interconnected by means of a series arrangement that includes a load circuit comprising at least the lamp (1) and an induction coil (5), and a first semiconductor switching element (6) including a freewheel diode. The load circuit is bridged by a circuit including a second semiconductor switching element (7) with a freewheel diode. The semiconductor switching elements (6, 7) are provided with control circuits for rendering said switching elements alternately conducting. The control circuit (9) of switching element (7) has a voltage measuring point which is connected via a rectifier element (10) to the control circuit (8) of the first switching element.