Abstract: The present invention relates generally to a simple, low cost ballast for fluorescent lamps that incorporates an integrated circuit and a number of ballast protection functions to cost effectively enhance its reliability. End of lamp life circuitry is provided to shut down the ballast when rectification currents due to lamp aging exceed a predetermined level. This circuitry also functions to stop the ballast operation when the lamp's voltage exceeds a predetermined cutoff level for a set period of time. Re-ignition circuitry is provided that restarts the ballast when new lamps are installed without shutting off the ballast. Multiple striking attempt circuitry is provided that initiates a predetermined number of striking attempts such that cold or old lamps are quickly ignited without the introduction of excessive flickering.

Abstract: Electronic ballast power supply/control circuits and methods that can be used to supply starting power to PFC control chips and that can be used to control ballasts so that PFC and inverter power supply circuits supply stable power to control circuitry even when the ballasts are performing advanced ballast functions. The circuits and methods supply starting power more quickly and efficiently than prior art starting circuits and control ballasts by either loading PFC circuits or inverter circuits included in the ballasts. The circuits load PFC circuits by connecting load resistors to the PFC circuits or by operating the inverter circuits at high frequencies that generate switching losses in the inverter transistors that load the PFC circuits. Inverter circuits are loaded by operating the inverter at frequencies that are much higher than preheating, igniting, and normal operating frequencies.

Abstract: The present invention relates generally to a simple, low cost ballast for fluorescent lamps that incorporates an integrated circuit and a number of ballast protection functions to cost effectively enhance its reliability. End of lamp life circuitry is provided to shut down the ballast when rectification currents due to lamp aging exceed a predetermined level. This circuitry also functions to stop the ballast operation when the lamp's voltage exceeds a predetermined cutoff level for a set period of time. Re-ignition circuitry is provided that restarts the ballast when new lamps are installed without shutting off the ballast. Multiple striking attempt circuitry is provided that initiates a predetermined number of striking attempts such that cold or old lamps are quickly ignited without the introduction of excessive flickering.

Abstract: An instant-start ballast for a multiple gas discharge lamp fixture has a single half-bridge inverter that is used to drive at least two series resonant output circuits. Each series resonant output circuit is used to drive two gas discharge lamps. A single output voltage limiting circuit is provided with a microprocessor that monitors the combined output voltages of the series resonant output circuits and uses a single voltage limiting transistor to control the output voltages of the circuits. A capacitor is associated with each gas discharge lamp socket in the fixture such that a voltage across the capacitor indicates that a lamp has been installed in the socket associated with the capacitor. The ignition sequence will only be initiated if the capacitor voltages indicate that a lamp has been installed in each socket of a fixture.

Abstract: An electronic ballast uses a voltage sampling circuit and a voltage control circuit to limit the open circuit voltage of the ballast. A lamp voltage sensing circuit is provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A resistor placed in series with the sampling capacitor is used to create a voltage that turns a control transistor off and on. The control transistor produces a gating signal trimming signal that a half bridge driver uses to alter the gating signals provided to the inverter transistors of the ballast. A cable compensation circuit is included that minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by turning the control transistor off and on.

Abstract: An improved high input voltage instant start electronic ballast uses a substantially lossless snubber circuit. The substantially lossless snubber circuit is incorporated into the ballast to reduce turn off losses and increase the efficiency of the ballast. The snubber circuit includes two capacitors connected in parallel with respect to the two switching transistors or FETS in the inverter of the ballast. A series-resonant lamp voltage sensing circuit is also provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A cable compensation circuit minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by limiting the turn on times of the transistors during high voltage conditions.

Abstract: An electronic ballast has a resonant tank circuit that includes a tank inductor and a tank capacitor connected in series. Lossless sampling of the output voltage of the electronic ballast is achieved by monitoring the voltage across a sampling capacitor placed in series with the tank capacitor. A resistive and capacitive filter is used to filter the monitored voltage such that it can be accurately received by a microcontroller. A resistor is connected in series with the sampling capacitor to produce an open circuit output voltage control signal that is used by the microcontroller to limit the open circuit output voltage. A cable compensation circuit is utilized to minimize variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast output terminals.

Abstract: Electronic ballast power supply/control circuits and methods that can be used to supply starting power to PFC control chips and that can be used to control ballasts so that PFC and inverter power supply circuits supply stable power to control circuitry even when the ballasts are performing advanced ballast functions. The circuits and methods supply starting power more quickly and efficiently than prior art starting circuits and control ballasts by either loading PFC circuits or inverter circuits included in the ballasts. The circuits load PFC circuits by connecting load resistors to the PFC circuits or by operating the inverter circuits at high frequencies that generate switching losses in the inverter transistors that load the PFC circuits. Inverter circuits are loaded by operating the inverter at frequencies that are much higher than preheating, igniting, and normal operating frequencies.

Abstract: An electronic ballast has a resonant tank circuit that includes a tank inductor and a tank capacitor connected in series. Lossless sampling of the output voltage of the electronic ballast is achieved by monitoring the voltage across a sampling capacitor placed in series with the tank capacitor. A resistive and capacitive filter is used to filter the monitored voltage such that it can be accurately received by a microcontroller. A resistor is connected in series with the sampling capacitor to produce an open circuit output voltage control signal that is used by the microcontroller to limit the open circuit output voltage. A cable compensation circuit is utilized to minimize variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast output terminals. 17.

Abstract: An improved high input voltage instant start electronic ballast uses a substantially lossless snubber circuit. The substantially lossless snubber circuit is incorporated into the ballast to reduce turn off losses and increase the efficiency of the ballast. The snubber circuit includes two capacitors connected in parallel with respect to the two switching transistors or FETS in the inverter of the ballast. A series-resonant lamp voltage sensing circuit is also provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A cable compensation circuit minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by limiting the turn on times of the transistors during high voltage conditions.

Abstract: An instant-start ballast for a multiple gas discharge lamp fixture has a single half-bridge inverter that is used to drive at least two series resonant output circuits. Each series resonant output circuit is used to drive two gas discharge lamps. A single output voltage limiting circuit is provided with a microprocessor that monitors the combined output voltages of the series resonant output circuits and uses a single voltage limiting transistor to control the output voltages of the circuits. A capacitor is associated with each gas discharge lamp socket in the fixture such that a voltage across the capacitor indicates that a lamp has been installed in the socket associated with the capacitor. The ignition sequence will only be initiated if the capacitor voltages indicate that a lamp has been installed in each socket of a fixture.

Abstract: An electronic ballast uses a voltage sampling circuit and a voltage control circuit to limit the open circuit voltage of the ballast. A lamp voltage sensing circuit is provided that uses a voltage dividing capacitor to accomplish lossless monitoring of the open circuit voltage of the ballast. A resistor placed in series with the sampling capacitor is used to create a voltage that turns a control transistor off and on. The control transistor produces a gating signal trimming signal that a half bridge driver uses to alter the gating signals provided to the inverter transistors of the ballast. A cable compensation circuit is included that minimizes variations in the open circuit voltage due to the connecting and disconnecting of a cable to the ballast by turning the control transistor off and on.

Abstract: An LED light source drive includes an LED current generating circuit and an LED drive controller. The current generating circuit is operable to receive power from a power source and to generate a dc current that can be used to the drive an LED light source. The drive controller is operable to control the dc current to ensure that the light output of the light source remains approximately constant over its operating lifetime. In one embodiment, the drive controller ensures that the effective light output of the light source remains approximately constant by automatically increasing the dc current in predetermined amounts at predetermined times. In an alternative embodiment, the drive controller includes an LED light sensor that is operable to generate a light signal indicative of the effective light output of the light source and the controller uses this light signal to control the dc current output.