Abstract: A dimming control system includes a first circuit (100) and a second circuit (200). First circuit (100) is coupled in series with the AC line source (10) and receives brighten and dim commands from a user. The brighten and dim commands are communicated to second circuit (200) by momentarily altering the AC voltage waveforms observed by second circuit (200). Second circuit (200) provides an adjustable dimming control voltage that is coupled to existing dimming control circuitry within an electronic dimming ballast. The dimming control voltage is adjusted by the second circuit (200) in dependence on the observed AC voltage waveforms.

Abstract: A ballast (10) for powering a gas discharge lamp includes a lamp-out detection circuit (300) that quickly responds to a lamp-out condition. Lamp-out detection circuit (300) receives a portion of the lamp current and provides a detection voltage. The detection voltage remains at a first average level while the lamp is conducting current in a normal manner, but quickly decreases below a second level if the lamp ceases to conduct current. In a preferred embodiment, ballast (10) includes an inverter (100) and a resonant circuit (210,220) that are normally operated at a high frequency. The detection voltage is coupled to an enable input (112) of an inverter drive circuit (110), and the inverter (100) is either shut off or operated in a low-power mode within less than ten high frequency cycles after occurrence of a lamp-out condition.

Abstract: A ballast (10) for powering a gas discharge lamp (20) having heatable filaments (22,24) includes a filament heating and protection circuit (300) that provides preheating of the filaments, efficiently reduces the filament heating power after the lamp ignites, quickly responds to removal or failure of the lamp in order minimize power dissipation in the ballast, and operates a replaced lamp without requiring cycling of the power to the ballast. In a preferred embodiment, filament heating and protection circuit (300) includes a transformer (400), a switching circuit (600), a turn-on circuit (700), and a lamp-out detection circuit (800).

Abstract: A ballast (10) for powering a discharge lamp (70) comprises a source of direct current (100), an inverter (600), and an output circuit (700). Output circuit (700) provides high voltage starting pulses for igniting the lamp, and may be implemented with either a single-tapped inductor (720) or with dual tapped inductors (720,740). Preferably, inverter (600) may be realized as either a half-bridge inverter (600) or a full-bridge inverter (600′) that operates at a relatively low frequency so as to avoid acoustic resonance effects in the lamp. DC current source (100) provides a limited source of current and may be realized as either a dual current source (100) for powering a half-bridge inverter (600), or a single current source (100′) for powering a full-bridge inverter (600′).

Abstract: An arrangement for protecting low-voltage control circuitry from externally applied high voltages comprises a voltage source (30) and a current-sourcing circuit (40). Current-sourcing circuit (40) provides current to an external controller (18) in a normal manner when an external source of high voltage is not applied to the output connections (42,44), protects itself (40) and the voltage source (30) from damage when an external source of high voltage is applied to the output connections (42,44), and provides current to the external controller (18) in a normal manner after the external source of high voltage is subsequently removed from the output connections (42,44). The arrangement may be employed as the dimming interface circuit (900) of an electronic dimming ballast (60) for gas discharge lamps to protect ballast circuitry from damage due to wiring errors during installation.

Abstract: A ballast (10) for powering a discharge lamp (20) comprises an output circuit (300) and a lamp starting circuit (400). The output circuit (300) includes a resonant inductor (310), a resonant capacitor (312), and a direct current (DC) blocking capacitor (314). Lamp starting circuit (400) is magnetically coupled to the resonant inductor (310) and supplies charging current to the DC blocking capacitor (314). The resulting high voltage that is developed across the DC blocking capacitor (314) ignites the lamp (20). In a preferred embodiment, lamp starting circuit (400) includes a starting winding (402), a current-limiting capacitor (406), a first rectifier (410), and a second rectifier (416).

Abstract: An electronic ballast (10) for fluorescent lamps includes a rectifier circuit (100), a boost converter (200), and an inverter (500). The boost converter (200) includes a boost control circuit (400) and a shifting circuit (300). The shifting circuit (300) provides filament preheating by maintaining the boost output voltage at a first level for a predetermined delay period following startup of the boost converter, and then increasing the boost voltage to a second level upon completion of the delay period in order to ignite and operate the lamps. In a preferred embodiment, shifting circuit (300) comprises a shunt circuit (320) and a time delay circuit (360), and inverter (400) is a series resonant half-bridge inverter.

Abstract: An electronic ballast (10) for powering at least one gas discharge lamp (30) includes a rectifier circuit (100), a line blocking rectifier (220), a bulk capacitor (240), an inverter (300), an output circuit (400), and a charging circuit (500). Charging circuit (500) is coupled between the output circuit (400) and the bulk capacitor (240) and provides operating current to the bulk capacitor (240). Charging circuit (500) also protects lamp life by preventing excessive flow of DC current in the lamp (30) following application of AC power to the ballast (10). In a preferred embodiment, charging circuit (500) includes a DC blocking capacitor (510), a lamp current blocking rectifier (530), and a charging rectifier (540).

Abstract: An electronic ballast (100) for powering at least one gas discharge lamp (10) comprises an inverter (200) and an output circuit (300). Output circuit (300) comprises a resonant inductor (310), a resonant capacitor (330), a DC blocking capacitor (360), a first rectifier (350), and a second rectifier (370). Output circuit (300) prevents excessive current flow and power dissipation in the event of lamp removal or failure, and provides automatic ignition following lamp replacement. In an alternative embodiment, a ballast (160) for powering two lamps (10,20) includes a pair of modified output circuits (500,600) and a ground-referenced lamp return wire (504) for accommodating conventional instant-start type wiring.

Abstract: An electronic power supply (10) comprising a rectifier circuit (100) and a voltage converter circuit (200). Voltage converter circuit (200) comprises a first inductor (220), a second inductor (230), an electronic switch (240), a control circuit (300), a first rectifier (250), a second rectifier (260), a first capacitor (270), and a second capacitor (280). First inductor (220) and second inductor (230) may be implemented either as separate inductors or as coupled inductors. Power supply (10) efficiently provides a high output voltage with greater efficiency than conventional boost converters.

Abstract: An electronic ballast (200) includes a rectifier circuit (20), a clamp inductor (44), an electronic switch (62), a control circuit (60) for driving the electronic switch (62), an energy storage capacitor (34), a first diode (38), a second diode (50), a clamping capacitor (58), and an output circuit (80). In a preferred embodiment, the rectifier circuit (20) includes a full-wave diode bridge (22) and a high frequency filter capacitor (24), and the output circuit (80) has a resonant inductor (82), a resonant capacitor (92), and a DC blocking capacitor (98). The ballast (200) provides power factor correction, low in-rush current, and high frequency power for fluorescent lamps, but requires only a single electronic switch (62) and a single clamp inductor (44).

Abstract: An electronic ballast (100) for powering at least one gas discharge lamp (10) comprises an inverter (300), an output circuit (400), and a switching circuit (500). Output circuit (400) includes a resonant inductor (440) and a resonant capacitor (460). Switching circuit (500) is coupled between the resonant capacitor (460) and an AC ground node such as circuit ground node (60), and is operable to effectively disconnect the resonant capacitor (460) after the lamp (10) ignites, thereby eliminating circulating current and significantly enhancing ballast energy efficiency. Switching circuit preferably comprises an electronic switch (600) and a pulse circuit (700), and optionally includes a diode matrix for use in ballasts for powering two or more lamps. In one embodiment, pulse circuit (800) monitors for lamp replacement and provides automatic ignition of a replaced lamp.

Abstract: An electronic power supply circuit (50) that includes a rectifying circuit (14), a boost converter (16), an in-rush current reduction circuit (52), and a bulk capacitor (18). The in-rush current reduction circuit (52) includes an in-rush current limiting resistor (54) and a bypass capacitor (56) that are connected in parallel with each other. An improved version of the in-rush current reduction circuit (52) includes a bypass diode (58) connected in parallel with the in-rush current limiting resistor (54) and bypass capacitor (56) which is oriented to provide a path for current flowing out of bulk capacitor (18). One particular application of the disclosed circuit is for use in an electronic ballast for fluorescent lamps.

Abstract: An electronic ballast (10) for powering at least one gas discharge lamp (20) comprising an AC-to-DC converter (100), an inverter (200), an output circuit (300), a relamping circuit (400), and an inverter protection circuit (500). Protection circuit (500) shuts down the inverter (200) in response to lamp removal or lamp failure. Following replacement of a failed lamp with an operational lamp, relamping circuit (400) provides restarting of the inverter (200) and ignition of the operational lamp by momentarily disabling the inverter protection circuit (500).

Abstract: A power supply (10) for powering a load (500) includes an inverter (100), a series resonant output circuit (200), and a bootstrap power source (300) for supplying operating power to an inverter driver circuit (110). The bootstrap power source (300) is coupled in series with the load (500) via a dc blocking capacitor (240) and provides automatic shutdown of the inverter (100) by ceasing to supply operating power to the inverter driver circuit (110) when the load (500) fails to conduct current or is removed.

Abstract: An electronic power supply (10) includes a boost converter (100) and an inverter (600). The inverter (600) includes a first inverter node (602) having a periodically varying voltage, and a second inverter node (604) having a voltage with a peak value that is proportional to the dc output voltage of the boost converter (100). The boost converter (100) includes a control circuit (200) for driving a boost FET (110). Control circuit (200) includes a shunt circuit (300) having a shunt switch (308) for periodically turning off the boost FET (110), a drive source network (400) that is coupled to the first inverter node (602), and a load regulation network (500) that is coupled to the second inverter node (604). In a preferred embodiment, the power supply (10) includes a rectifier circuit (40) and a push-pull inverter (600), and is adapted to serve as an electronic ballast for powering at least one fluorescent lamp (702).

Abstract: An electronic ballast (200) includes a rectifier circuit (20), an energy storage inductor (38), a power switch (58), a control circuit (50) for driving the power switch (58), a clamp diode (46), a voltage clamping capacitor (54), a bulk capacitor (34), and an output circuit (70) for providing power to one or more fluorescent lamps (100). In a preferred embodiment, the rectifier circuit (20) includes a full-wave diode bridge (22) and a high frequency filter capacitor (24), and the output circuit (70) has a resonant inductor (72), a resonant capacitor (82), and a dc blocking capacitor (88). The ballast (200) provides power factor correction and high frequency power for fluorescent lamps, but requires only a single power switch (58) and a single energy storage inductor (38).

Abstract: A power-line communication system (10) for use with a conventional AC source (12) having a hot wire (14) and a neutral wire (16). The communication system (10) includes a pulse transmitter (16) and at least one receiver (18) connected downstream from the pulse transmitter (16). The pulse transmitter (16) is coupled between the hot wire (14) of the AC source (12) and either the neutral wire (16) of the AC source (12) or earth ground. Each receiver (14) is coupled to the AC source (12). The pulse transmitter (16) includes a control circuit (30) for controlling the conduction of a shunt circuit (32) and sends messages to the receivers (20) by inducing momentary pulses in the AC voltage supplied by the AC source (12). The shunt circuit (32) includes a power switch (52) and an energy clamp circuit for limiting the amplitude and the duration of the current through the power switch (52) and the pulse induced in the AC line voltage.

Abstract: A ballast circuit for driving a gas discharge having a source of pulsating and rectified AC (20), an energy storage circuit (30), a switch (40) that can have one end connected to an energy storage inductor and an opposite end that can be connected to circuit common; a control circuit (50) for opening and closing the switch (40) at a rate that is a function of at least a DC control current, a resonant circuit (60) that is coupled to the energy storage circuit (30) for energizing the gas discharge lamp.

Abstract: An electronic ballast having a boot strap capacitor 22 that becomes initially charged at a first rate and a high voltage storage capacitor 23 that becomes charged at a second, faster rate, wherein the boot strap capacitor 22, becoming initially fully charged initiates operation of a PWM driver 18 that in turn causes a power factor corrector and inverter 16 to energize corresponding gas discharge lamps 11. Upon activation of the PWM driver 18 and the corresponding activation of the power factor corrector and inverter 16, a voltage clamp 19 responds to these events by establishing a conductive path 20 between the high voltage storage capacitor 23 and the boot strap capacitor 22, such that continued operation of the PWM driver 18 is ensured. So configured, a relatively small valued capacitor can be utilized for the boot strap capacitor 22, thereby ensuring rapid activation of the lamps 11 without risking subsequent sporadic energization or other operational difficulties.