Abstract: A converter for an LED driver for an LED light source. The converter has a flyback transformer. The primary receives a rectified AC voltage. A switching transistor is coupled in series with the primary. A controller controls the switching transistor on and off to generate a bus voltage across the secondary and a center tap voltage at a center tap of the secondary. The controller is powered by a first low-voltage DC voltage. A first power supply receives the center tap voltage and generates a second low-voltage DC voltage when the center tap voltage is above a cutover voltage. A second power supply has an output coupled to the first power supply output. The second power supply receives the bus voltage and generates the second DC voltage when the center tap voltage is below the cutover voltage.

Abstract: A load control device, such as an electronic ballast, for controlling the power delivered from an AC power source to an electrical load, such as one or more fluorescent lamps, comprises a power converter having an inductor and a power switching device coupled to the inductor, a load control circuit adapted to be coupled to the electrical load, and a control circuit operable to calculate an average input power of the load control device. The control circuit may be operable to calculate a cumulative output power of the power converter while the ballast is preheating filaments of the lamps, and to subsequently determine a fault condition in the lamps in response to the calculated cumulative output power of the power converter. Further, the control circuit may be operable to transmit a digital message including the calculated average input power of the load control device.

Abstract: A configurable light-emitting diode (LED) driver is adapted to control a plurality of different LED light sources, which may be rated to operate using different load control techniques, different dimming techniques, and different magnitudes of load current and voltage. The LED driver comprises a power converter circuit for generating a DC bus voltage, and an LED drive circuit for receiving the bus voltage and adjusting either the magnitude of the current conducted through the LED light source or the magnitude of the voltage across the LED light source. The LED driver is operable to dim the LED light source using either a pulse-width modulation technique or a constant current reduction technique, and may be configured using a programming device and a personal computer.

Abstract: A light-emitting diode (LED) driver is adapted to control either the magnitude of the current conducted through a LED light source or the magnitude of a voltage generated across the LED light source. The LED driver comprises a power converter circuit for generating a DC bus voltage, and an LED drive circuit for receiving the bus voltage and adjusting the magnitude of the current conducted through the LED light source. The LED driver is operable to dim the LED light source using either a pulse-width modulation technique or a constant current reduction technique. The LED drive circuit may comprise a controllable-impedance circuit, such as a linear regulator. The LED driver may be operable to control the magnitude of the bus voltage to optimize the efficiency and reduce the power dissipation in the LED drive circuit, as well ensuring that the load voltage and current do not have any ripple.

Abstract: A load control circuit, such as a light-emitting diode (LED) driver, for controlling the amount of power delivered to an electrical load, such as an LED light source, comprises a regulation transistor adapted to be coupled in series with the load, and a feedback circuit coupled in series with the regulation transistor, whereby the load control circuit is able to control the magnitude of a load current conducted through the load from a minimum load current to a maximum load current, which is at least approximately one thousand times larger than the minimum load current. The feedback circuit generates at least one load current feedback signal representative of the magnitude of the load current. The regulation transistor operates in the linear region to control the magnitude of the load current conducted through the load in response to the magnitude of the load current determined from the load current feedback signal.

Abstract: An electronic ballast for driving a gas discharge lamp comprises an inverter circuit, a resonant tank circuit, and a control circuit operable to determine an approximation of a resonant frequency of the resonant tank circuit and to control the inverter circuit in response to the approximation of the resonant frequency. The control circuit determines the approximation of the resonant frequency by adjusting an operating frequency of a high-frequency inverter output voltage provided to the resonant tank circuit from a frequency above the resonant frequency down towards the resonant frequency, measuring the magnitude of a lamp voltage across the lamp, and storing the present value of the operating frequency as the resonant frequency when the magnitude of the lamp voltage reaches a maximum value. The control circuit may control the operating frequency of the inverter output voltage in response to the approximation of the resonant frequency and a target intensity of the lamp.

Abstract: A converter for an LED driver for an LED light source. The converter has a flyback transformer. The primary receives a rectified AC voltage. A switching transistor is coupled in series with the primary. A controller controls the switching transistor on and off to generate a bus voltage across the secondary and a center tap voltage at a center tap of the secondary. The controller is powered by a first low-voltage DC voltage. A first power supply receives the center tap voltage and generates a second low-voltage DC voltage when the center tap voltage is above a cutover voltage. A second power supply has an output coupled to the first power supply output. The second power supply receives the bus voltage and generates the second DC voltage when the center tap voltage is below the cutover voltage.

Abstract: A system for configuring an output parameter of a lighting load power supply, the power supply having a programmable controller for regulating the output parameter to a target value and a memory for storing a variable for setting the target value. The power supply has a communication port for data for setting the target value. A computer executes software allowing a user to select a target value and provides data related to the selected parameter. A programming device in communication with the computer provides data relating to the selected parameter to the communication port for programming the controller to set the parameter to the target value.

Abstract: An electronic ballast for driving a gas discharge lamp comprises an inverter circuit, a resonant tank circuit, and a control circuit operable to determine an approximation of a resonant frequency of the resonant tank circuit and to control the inverter circuit in response to the approximation of the resonant frequency. The control circuit determines the approximation of the resonant frequency by adjusting an operating frequency of a high-frequency inverter output voltage provided to the resonant tank circuit from a frequency above the resonant frequency down towards the resonant frequency, measuring the magnitude of a lamp voltage across the lamp, and storing the present value of the operating frequency as the resonant frequency when the magnitude of the lamp voltage reaches a maximum value. The control circuit may control the operating frequency of the inverter output voltage in response to the approximation of the resonant frequency and a target intensity of the lamp.

Abstract: A load control device, such as an electronic ballast, for controlling the power delivered from an AC power source to an electrical load, such as one or more fluorescent lamps, comprises a power converter having an inductor and a power switching device coupled to the inductor, a load control circuit adapted to be coupled to the electrical load, and a control circuit operable to calculate an average input power of the load control device. The control circuit may be operable to calculate a cumulative output power of the power converter while the ballast is preheating filaments of the lamps, and to subsequently determine a fault condition in the lamps in response to the calculated cumulative output power of the power converter. Further, the control circuit may be operable to transmit a digital message including the calculated average input power of the load control device.

Abstract: An electronic ballast circuit for driving a gas discharge lamp is operable to control the lamp to avoid flicking and flashing of the intensity of the lamp during low temperature conditions. The ballast circuit includes an inverter circuit for receiving a DC bus voltage and for generating a high-frequency output voltage, a resonant tank circuit for receiving the high-frequency output voltage and generating a sinusoidal voltage for driving said lamp, and a control circuit operatively coupled to the inverter circuit for adjusting an intensity of the lamp between a minimum intensity and a maximum intensity. The control circuit receives a control signal representative of a lamp temperature of the lamp, and increases the minimum intensity of the lamp if the lamp temperature of the lamp drops below a cold temperature threshold. In addition, the ballast circuit may also include a temperature sensing circuit operable to generate the control signal representative of the lamp temperature of the lamp.

Abstract: A communication circuit for an electronic dimming ballast provides high-voltage miswire protection and improved rise and fall times of a transmitted digital signal. The electronic dimming ballast comprises a control circuit, which is coupled to a digital communication link, for example, a DALI communication link, via the communication circuit. The communication circuit comprises a receiving circuit for detecting when the digital ballast communication link is shorted and for providing a received digital message to the control circuit. The communication circuit also comprises a transmitting circuit for shorting the communication link in response to the control circuit. The communication circuit also includes a high-voltage fault protection circuit for protecting the circuitry of the communication circuit if the communication circuit high-voltage mains voltages. The communication circuit is operable to reliably transmit digital messages having improved rise and fall times.

Abstract: The output current of a ballast is dynamically limited when an over-temperature condition is detected in the ballast according to one of (i) a step function or (ii) a combination of step and continuous functions, so as to reduce the temperature of the ballast while continuing to operate it.

Abstract: A load control circuit, such as a light-emitting diode (LED) driver, for controlling the amount of power delivered to an electrical load, such as an LED light source, comprises a regulation transistor adapted to be coupled in series with the load, and a feedback circuit coupled in series with the regulation transistor, whereby the load control circuit is able to control the magnitude of a load current conducted through the load from a minimum load current to a maximum load current, which is at least approximately one thousand times larger than the minimum load current. The feedback circuit generates at least one load current feedback signal representative of the magnitude of the load current. The regulation transistor operates in the linear region to control the magnitude of the load current conducted through the load in response to the magnitude of the load current determined from the load current feedback signal.

Abstract: A light-emitting diode (LED) driver is adapted to control either the magnitude of the current conducted through a LED light source or the magnitude of a voltage generated across the LED light source. The LED driver comprises a power converter circuit for generating a DC bus voltage, and an LED drive circuit for receiving the bus voltage and adjusting the magnitude of the current conducted through the LED light source. The LED driver is operable to dim the LED light source using either a pulse-width modulation technique or a constant current reduction technique. The LED drive circuit may comprise a controllable-impedance circuit, such as a linear regulator. The LED driver may be operable to control the magnitude of the bus voltage to optimize the efficiency and reduce the power dissipation in the LED drive circuit, as well ensuring that the load voltage and current do not have any ripple.

Abstract: A configurable light-emitting diode (LED) driver is adapted to control a plurality of different LED light sources, which may be rated to operate using different load control techniques, different dimming techniques, and different magnitudes of load current and voltage. The LED driver comprises a power converter circuit for generating a DC bus voltage, and an LED drive circuit for receiving the bus voltage and adjusting either the magnitude of the current conducted through the LED light source or the magnitude of the voltage across the LED light source. The LED driver is operable to dim the LED light source using either a pulse-width modulation technique or a constant current reduction technique, and may be configured using a programming device and a personal computer.

Abstract: The output current of a ballast is dynamically limited when an over-temperature condition is detected in the ballast according to one of (i) a step function or (ii) a combination of step and continuous functions, so as to reduce the temperature of the ballast while continuing to operate it.

Abstract: The invention includes an electronic ballast that is operable to receive a ballast factor setting that enables the ballast to provide a desired ballast factor when the ballast drives a lamp. The electronic ballast includes an input that is adapted to receive a ballast factor setting that represents a desired ballast factor for the ballast and a respective lamp. The ballast further includes a memory that is adapted to store the ballast factor setting, and the ballast includes a processor that uses the ballast factor setting stored in the memory to cause the ballast to provide the desired ballast factor as the ballast drives the lamp. The ballast includes means for substantially preventing subsequently changing the ballast factor setting stored in the memory. Various business methods are further provided as a function of the electronic ballast.

Abstract: A method for assembling a lamp fixture incorporates a ballast and a compact gas discharge lamp into the fixture. A comparator circuit, clamp circuit, and control circuit are assembled into the ballast such that the comparator circuit compares a measured value of a lamp parameter to a threshold value and provides a signal indicative of the comparison; the clamp circuit receives the clamp signal and provides a clamp signal in accordance therewith; and the control circuit, in accordance with the clamp signal, controls the lamp such that the light level of the lamp can be lowered without perceptible flicker.

Abstract: An electronic ballast for driving a gas discharge lamp includes a rectifier to convert an AC mains input voltage to a rectified voltage, a filter circuit for producing a DC bus voltage, an inverter for converting the bus voltage to a high-frequency AC voltage for driving the lamp, an output circuit for supplying an essentially sinusoidal voltage to the lamp, a control circuit for controlling the inverter, and a flyback cat-ear power supply for powering the control circuit. The power supply supplies current to the inverter when the rectified voltage is less than a predetermined level, and draws current only when the inverter is not drawing current directly from the AC mains, so as to make the input current to the ballast substantially sinusoidal. The ballast thus has substantially improved power factor and THD, and operates more efficiently.