Abstract: An electronic ballast is provided with a filament heating circuit having a Q factor clamped at a certain range of preheat frequency. An inverter circuit includes a controller and a pair of switches coupled between positive and negative terminals of a power supply. The switches respond to control signals from the controller to oscillate at an operating frequency and generate an output voltage. An inverter tank is coupled to an inverter output terminal and includes a first capacitor, a primary winding of a filament heating transformer coupled on a first end in series with the first capacitor, a second capacitor coupled to the second end of the primary winding, and a clamping circuit coupled to the second capacitor. The clamping circuit during a preheat mode of operation clamps an amplitude of the voltage across the primary winding to an amplitude of the input voltage from the power supply.

Abstract: An occupancy detection network controls illumination from lighting devices in each of a plurality of defined areas. Motion detection modules and sound detection modules provide output signals based on detected occupancy in each defined area. The sound detection modules automatically adjust sorting criteria over time in accordance with identified sound characteristics associated with occupancy, detect sound in the associated defined area in accordance with the sorting criteria, and provide an output signal based on the detected sound. A central lighting controller is linked to the detection modules via a common bidirectional data bus. The controller receives an output signal, determines an occupancy state for the associated defined area, and controls lighting devices in the area to be turned on and off in accordance with the determined occupancy state.

Abstract: A lighting device such as an electronic ballast or LED driver includes circuitry to detect power converter activity and act accordingly. A power factor correction (PFC) circuit includes an inductor, a power converter switch, and a PFC controller effective to provide driving signals the power converter switch to turn on and off. A power converter activity detection circuit includes a first capacitor coupled between the PFC controller and the power converter switch, a zener diode, and a second capacitor coupled between the first capacitor and ground. An output voltage for the power converter activity detection circuit as referenced from a node between the first capacitor and the second capacitor is representative of activity by the power converter switch, and is provided to a lighting device controller which may accordingly maintain operation of the lighting device where a mains power interruption is only temporary but would otherwise disable the device.

Abstract: A lighting ballast includes a filament drive reduction circuit with a first inductor coupled across a filament drive source, and a second inductor and a capacitor coupled in parallel to define an LC tank between a first end of the first inductor and the filament drive source. The inductance value of the second inductor and the capacitance value of the capacitor are selected such that the natural resonance of the LC tank is substantially equal to the normal operating frequency of the filament drive source, wherein the LC tank acts as an open circuit during normal operation and the first inductor acts to balance the pin currents of series connected lamp filaments. The first and second inductors are further substantially equal in value, wherein excess filament drive current is shunted away in accordance with a normal operating frequency.

Abstract: A self-oscillating inverter provides an output voltage with fixed operating frequency and amplitude independently of a load. First and second switching elements are arranged in a half-bridge configuration. A resonant circuit having a primary winding of a resonant inductor and a resonant capacitor is coupled between the switching elements. A clamping circuit limits the voltage across the resonant capacitor to a predetermined maximum value, and along with the resonant capacitor defines a capacitance compensation circuit having an equivalent capacitance greater than that of the resonant capacitor alone, wherein the actual resonant frequency of the inverter is less than the natural frequency of the resonant circuit such that soft-switching is assured. An output voltage across the resonant inductor during steady-state operation is a quasi-square waveform with a fixed amplitude, wherein a load voltage across a secondary winding of the inductor is also a quasi-square waveform with a fixed amplitude.

Abstract: A power line communication system transmits a dimming level to an electronic ballast to regulate the power consumed by a lamp. The power line controller has a notch generation circuit that generates notches on an AC power signal with a time duration in accordance with the dimming level of the lamp. A dimming interface associated with the electronic ballast detects the notches on the AC power signal. The dimming interface generates a ballast dimming level signal with a signal level related to the time duration of these notches.

Abstract: A lighting device such as an electronic ballast or LED driver includes a power factor correction (PFC) controller responsive to input power supply signals to generate control signals, a PFC boost converter responsive to said control signals to generate a boosted output voltage, and a fast start circuit with a power supply source and an energy storage device, a magnitude of the input power supply signal corresponding to energy stored in the energy storage device. During a first mode, the fast start circuit responds to a rectified mains input to enable the power supply source and charge the energy storage device. During a second mode, the fast start circuit responds to a magnitude of the power supply signal to disable the power supply source and discharge the energy storage device. The boost converter during the second operating mode maintains controller operation while the power supply source is disabled.

Abstract: A control signal interface circuit includes a line voltage protection circuit coupled to first and second input terminals. The protection circuit provides an input DC voltage across the input terminals within a predetermined range (i.e., 0-10 Vdc) and prevents the application of an input line voltage (i.e., 347 Vac) across the input terminals. A first current source circuit is coupled to the protection circuit, an isolation circuit is coupled to the first current source circuit and a second current source circuit is coupled to the isolation circuit. The first and second current source circuits collectively provide a linear output DC voltage with respect to the input DC voltage. At least one of the first and second current source circuits include circuitry wherein the linear conversion of the input DC voltage to the output DC voltage is independent of the temperature.

Abstract: A lamp ballast is provided for igniting and operating an HID lamp. A buck inverter circuit includes a pair of high-frequency and a pair of low-frequency switches. A capacitor and an inductor are series-connected between a first node between the low frequency switches and a second node between the high frequency switches. A lamp igniting circuit is coupled between the first node and a first lamp output terminal, and a second lamp output terminal is coupled to a third node between the capacitor and the inductor. A control circuit turns on and off the switches to regulate low frequency square wave voltage generated across the lamp output terminals to be less than an input DC voltage from the positive rail, wherein the buck inverter operates in either of a critical discontinuous mode or a discontinuous mode during an open circuit operation, and in a critical discontinuous mode during other operations.

Abstract: A universal dimming topology is provided for an electronic ballast having an inverter providing an output current across first and second output branches for driving a light source in accordance with a dimming control input signal. A filament voltage control block modulates first and second filament heating switches to provide filament heating voltage across first and second connection terminals associated with the output branches. During a preheat operating mode a control block disables the inverter and provides pulse width modulated control signals to the filament voltage control block to modulate the filament heating switches at a predetermined frequency. During a normal operating mode the control block enables the inverter and provides pulse width modulated control signals to the filament voltage control block to modulate the filament heating switches in accordance with a duty ratio based on a detected output current.

Abstract: An electronic ballast is provided with circuitry for detecting the removal of one or more lamp filaments across a range of dimming levels, and regulating an output stage including at least first and second pairs of lamp connection output terminals based on a filament connection status. A filament removal sensing circuit is coupled to the output terminal pairs and configured to generate an output voltage representative of a filament connection status with respect to the output terminal pairs. A microcontroller is coupled to receive the output voltage from the filament removal sensing circuit and programmed to determine a rate of change in the output voltage, compare the rate of change in the output voltage to a predetermined threshold value, and disable the output stage when the rate of change in the output voltage exceeds the predetermined threshold value.

Abstract: An asymmetric end-of-life protection circuit with single-point voltage measurement is provided for an electronic ballast having two lamp connection terminals. A grounding circuit includes a capacitor and a first resistor coupled in parallel between a first lamp connection terminal and ground, and is effective to drain the second lamp connection terminal to ground. A lamp voltage detection circuit is coupled between the first lamp connection terminal and ground and measures the lamp voltage from the first lamp connection terminal. A controller is effective to shut down the ballast based on an output signal from the lamp voltage detection circuit being greater than a first predetermined threshold value or less than a second predetermined threshold value.

Abstract: A system and method are provided for powering a lighting device having one or more arrays of LEDs. Three current sourcing circuits each include a switching element having a source coupled to an input power source. A microcontroller includes a processor, a communications module, an internal clock oscillator, a counter, and program instructions executable to cause the processor to carry out the control functions. Desired light intensity levels are stored as individual output level data, and pulse density modulated output values are generated for each of the stored output level data using carry overflow logic. The generated output values are converted to output signals and provided to the respective current sourcing circuits, wherein current is sourced through the switching elements to respective LEDs of a given color based on a pulse density modulated signal applied to the gates of the respective switching elements.

Abstract: A magnetic component provides both electrical interconnectivity and mechanical support between stacked circuit boards. The magnetic component includes a bobbin structure and a magnetically permeable core. The bobbin structure includes an upper bobbin pin rail and a lower bobbin pin rail. The upper bobbin pin rail includes one or more upper bobbin pins extending from the upper bobbin pin rail. Each upper bobbin pin may be adapted for soldering onto a first circuit board. At least one lower bobbin pin extends from the lower bobbin pin rail. Each lower bobbin pin may also be adapted for soldering onto a second circuit board, forming a circuit board assembly. Each soldered connection between a bobbin pin and a circuit board may provide an electrical connection between the circuit board and the magnetic component. Each soldered connection may also provide a mechanical attachment between a printed circuit board and the magnetic component.

Abstract: An inrush protection circuit is provided for an electronic ballast for powering HID lamps. A first resistor is positioned along a low potential side of the circuit and a switching element coupled in parallel with the first resistor. Second and third resistors are coupled in series and effective to receive DC input power from a DC source, with a first node between the second and third resistors further coupled to the gate of the switching element. A capacitor is coupled in parallel with the third resistor to provide a smoothed DC voltage to the gate of the switching element. A discharging circuit includes a diode and a fourth resistor coupled in series between the first node and the high potential side of the circuit, and is arranged to conduct discharging current from the capacitor until the voltage across the capacitor discharges below a predetermined voltage after the DC input power is removed from the circuit.

Abstract: An electronic ballast is provided and a method for operating one or more lamps. The ballast and method provide for true parallel lamp operation, with preheating of lamp filaments during a dimming operation. Switching losses are reduced by ensured soft switching operation. An inverter switch driver is arranged to provide first drive signals to a shared line branch having a first switch shared among a plurality of decoupled inverter drive modules and to provide second drive signals to a plurality of independent line branches each having a switch and associated with one of the decoupled inverter drive modules. A soft switching control circuit is coupled to the first switch and configured so as to maintain a soft switching operation for the first switch.

Abstract: A mounting apparatus for a light emitting diode module provides a support structure for attaching a light emitting diode module directly to a light bulb in a lighting system. A bulb bracket includes a bulb clip that can be mechanically attached to a conventional bulb such as a fluorescent, neon or incandescent light bulb. A light emitting diode module can be secured to the bulb bracket using a module clip or another attachment means disposed between the bracket and the module. Additional light emitting diode support structures include a mounting bar securable directly to a light bulb or other structure in a lighting system such as a sign box wall. An expandable support bracket is also provided for supporting one or more light emitting diode modules. A method of retrofitting a lighting system to use a light emitting diode module is also provided.

Abstract: A zone addressing circuit is provided for an electronic ballast having a boost inductor with an auxiliary winding. The zone addressing circuit includes a first circuit branch coupled to a first addressing input terminal, a second circuit branch coupled to a second addressing input terminal, and a third (common) branch coupled on a first end to a third addressing input terminal and on a second end to the auxiliary winding of the boost inductor for providing a high frequency input pulse signal to excite the first and second branches. The first branch generates a first digital output for the zone addressing circuit when coupled to the common branch, and the second branch generates a second digital output for the zone addressing circuit when coupled to the common branch. A controller adjusts a dimming level of the ballast based on the first and second digital outputs from the zone addressing circuit.

Abstract: A dimmable and program start electronic ballast is configured for powering one or more lamps in a true parallel configuration. An inverter driver is coupled to each gate of a pair of inverter switches and is responsive to at least a reference input signal and a feedback input signal to drive the inverter switches. The inverter circuit is effective thereby to generate an output voltage at an inverter output terminal between the pair of switches. One or more tank circuits are coupled in parallel, with a first end of each coupled to the inverter output terminal. Each tank circuit has a switching circuit as well as first and second output terminals on a second end which can receive a discharge lamp filament. A controller is configured to adjust a switching state for each of the one or more switching circuits and thereby enable or disable an associated tank circuit.

Abstract: A power line communication system communicates a ballast dimming level to an electronic ballast over an AC power line. A power line controller is operable to generate the ballast control signal and to insert that signal on the AC power signal being transmitted over the AC power line. A power line receiver receives the AC power signal and extracts the ballast control signal from the AC power signal to generate the dimming level signal corresponding with the desired ballast dimming level. To insert the ballast control signal on the AC power signal, the power line controller has a transformer coupled to the signal pattern circuit. The secondary winding of this transformer is connected in series with the AC power line to insert the ballast control signal on the AC power signal. This AC power signal is then transmitted to the electronic ballast. To extract the ballast control signal out of the AC power signal, the power line receiver has a resonant circuit connected in series with the AC power line.