Abstract: A circuit arrangement for supplying a lamp with a DC lamp current and comprising only passive components and equipped with mains input terminals for connection to the poles of an AC supply voltage source. A rectifying apparatus has two input terminals coupled to the mains input terminals and two output terminals for generating a DC voltage from the low frequency AC supply voltage. A ballast capacitor is coupled between the mains input terminals and the output terminals of the rectifying apparatus. A load circuit is coupled to the output terminals of the rectifying apparatus and has terminals for connection to the lamp. The load circuit includes a series arrangement of only passive components which connect the output terminals of the rectifying apparatus and comprise an inductor and the terminals for connection to the lamp. The circuit arrangement is simple and inexpensive and is very suitable for operating a discharge lamp and for incorporation into a compact lamp.

Abstract: A driving circuit for bipolar transistors having a control voltage device for producing a control voltage associated with each transistor. A tertiary winding, serving as the base winding for the bipolar transistors, supplies current to the base of each bipolar transistor based on the associated control voltage. Separate feedback circuits associated with each transistor carry a feedback signal reflecting the minority carrier charge stored in the associated transistor. The control voltage associated with each transistor varies based on the associated feedback signal.

Abstract: MOS Cascode amplifier circuits are subject to long-term or instantaneous changes (degradation) of performance characteristics by excess substrate currents. These currents can be generated in the grounded source transistor of the cascode connected output transistors during peak excursions of drain-source voltage across the grounded source transistor when the output voltage of the MOS Cascode amplifier circuit is at a maximum. An improved MOS Cascode amplifier circuit arrangement includes a voltage limiting bias circuit arrangement of additional transistors. The bias circuit arrangement acts as a series voltage-limiting device between the MOS Cascode amplifier circuit output node and the drain node of the upper-most cascode connected transistors when the MOS Cascode amplifier circuit output voltage is at its maximum value.

Abstract: A dimming interface for translating the conduction pulse width of a signal produced by a triac dimmer into a proportional rectified average voltage serving as a dimming signal. The dimming signal is supplied as an input to an IC driver for controlling the level of lamp illumination. The proportional rectified average voltage can be converted into a signal representing a duty cylce whereby a variation in the mains line voltage does not affect the dimming signal.

Abstract: A compact flourescent lamp in which the level of illumination is controlled by a triac dimmer. Premature turn off of the triac dimmer is avoided through the serial combination of at least one resistor and at least one capacitor forming a snubber placed across the output of the electromagnetic interference filter of the compact flourescent lamp ballast. The snubber dampens oscillations generated within the compact flourescent lamp whereby sufficient power is drawn by the compact flourescent lamp to sustain conduction of the triac dimmer throughout the dimming range of the latter.

Abstract: A fluorescent lamp ballast having an integrated circuit driver which avoids lamp flicker caused by momentary dips in mains voltage during lamp turn on. The anti-flicker scheme within the fluorescent lamp ballast driver distinguishes between operating conditions during and after preheat of the lamp electrodes. By maintaining the voltage for powering the integrated circuit driver above its minimum threshold, the driver does not momentarily shut off during lamp turn on.

Abstract: A ballast including an inverter and a circuit having a resonant frequency coupled to the output of the inverter. In one embodiment of the invention, the only discrete type of element substantially affecting the resonant frequency is substantially inductive in electrical character. In this embodiment of the invention, there is also no discrete ballasting element in series with the lamp load. The reduction in discrete elements reduces both power consumption and costs associated with the ballast.

Abstract: A triac dimmable compact fluorescent lamp having a low power factor. A power feedback circuit coupled between the input and output stages of the lamp ballast creates sufficient current demand to sustain triac conduction at low dim levels. The power fed back from the output stage to the input stage, which includes a voltage doubler, reflects the voltage across the lamp.

Abstract: A circuit arrangement for use in a controller circuit of a switched mode power supply for turning on a power device in the switched-mode power supply when a voltage across the power device is at a minimum. The circuit arrangement includes circuitry for detecting when a change in the voltage across the power device is substantially zero, and for detecting when the voltage across the power device is less than a predetermined level. When these two criteria are met, the circuit arrangement generates a turn-on signal for the power device.

Abstract: A compact fluorescent lamp includes a ballast having a control circuit. The control circuit regulates the amount of power supplied to the lamp based on samples representing lamp current and lamp voltage. The sample of lamp voltage supplied to the control circuit is limited so that it cannot drop below a minimum level thereby preventing excessive levels of current from flowing through the lamp at low lamp voltage.

Abstract: A dimmable fluorescent lamp including a feedback circuit for drawing sufficient current to maintain an appropriate charge across the buffer capacitor. A bypass capacitor provides a path for diverting a portion of the power which would otherwise be fed back to the buffer capacitor during low level dimming. Consequently, overboost voltages across the buffer capacitor during low level dimming are substantially reduced.

Abstract: A light source including a ballast characterized by a resonant frequency and including a reference bus and a transformer having a secondary winding. The fluorescent lamp is partially covered by a shield, connected to the reference bus and coupled to the secondary winding. The ballast further includes a current sensor connected between the secondary winding and reference bus for sensing current flow through at least the lamp including that portion of lamp current attributable to parasitic capacitances affecting the resonant frequency.

Abstract: A circuit arrangement for supplying a controlled substantially constant level of electrical power to a discharge lamp in a load circuit includes a feedback loop responsive to a comparison or difference between a power measure signal corresponding to electrical power consumed by the lamp and a reference signal corresponding to a desired consumed power. The power measure signal is formed by a power measure signal forming circuit which includes a one quadrant multiplier which receives at a pair of inputs respective lamp voltage and lamp current measure signals output from a sample and hold device arranged for sampling both a signal indicative of instantaneous lamp voltage and a signal indicative of instantaneous lamp current. The sampling is done at instants at which a signal which is indicative of the derivative of the lamp voltage passes through zero in a predetermined direction.

Abstract: A circuit arrangement for the high-frequency operation of a discharge lamp comprises a first rectifying circuit (D1-D4) for generating a DC voltage across a first capacitor (C1) from a low-frequency supply voltage. A DC/AC converter (IV) for generating a high-frequency AC voltage at a frequency f from the DC voltage is coupled to a load branch (B) provided with coupling means (T3, T4) for coupling the discharge lamp (Li) to the load branch. The load branch connects a junction point N1 of the DC/AC converter to a junction point N2 between the first rectifying circuit and the first capacitor. A second rectifying circuit for converting a high-frequency voltage generated by the DC/AC converter into a DC voltage is coupled to the first capacitor and to a junction point N3 in the load branch. A control circuit controls the power consumed by the discharge lamp through variation of the frequency f. The coupling means are connected between the junction point N2 and the junction point N3 in the load branch.

Abstract: A ballast filter in which the ballast can operate at a total harmonic distortion of power line current of less than 10%. Power dissipated by the filter when at a THD of less than 10% is relatively low. The input impedance of the ballast is chosen to be no greater than twice the equivalent filter impedance of a front end filter and no less than the equivalent filter impedance/1.5. The filter includes a transformer having a core which at times operates within the non-linear region of its B-H curve under nominally rated ballast load conditions.