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), and an inverter protection circuit (400). Inverter protection circuit (400) includes a high voltage detection circuit (500), a no-load detection circuit (600), and a latch circuit (700), and is operable to turn off the inverter (200) in response to removal or failure of the gas discharge lamps. Inverter protection circuit (400) is well-suited for use in ballasts that power multiple, parallel-connected lamps and maintains operation of inverter (200) under a partially-loaded condition in which at least one operational lamp is present and each of the failed lamps has at least one open filament.

Abstract: An energy control system (10) comprises at least one controllable load (110), a master controller (200), a traveler wire (300) and at least one remote switch (400). The master controller (200) transmits control commands that effect corresponding control actions in the controllable load (110). The remote switch (400) transmits remote commands to the master controller (200) over the traveler wire (300). The energy control system (10) is well suited for installation in standard three-way switch or four-way switch electrical systems and requires neither additional wiring nor complicated installation procedures.

Abstract: A power transformer circuit (100) includes a capacitor (120) and a resonator (140). The resonator (140) is coupled in series with the capacitor (120) and is operable to provide a substantially inductive impedance between its terminals (142,144). Resonator (140) is preferably implemented as a piezoelectric lithium niobate resonator that is operated in a thickness-shear mode. In a preferred embodiment, power transformer circuit (100) is employed as a series resonant output circuit in an electronic ballast (500) for powering at least one gas discharge lamp (30).

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: A protection method (10) and protection circuit (500) for protecting an inverter (300) in an electronic preheat ballast (100) for powering at least one fluorescent lamp (902). The inverter (300) includes a first inverter switch (306), a second inverter switch (310), an output circuit (800), and an inverter driver circuit (400) having a drive frequency. The protection circuit (500) comprises a frequency shift circuit (600), a latch circuit (700), a current source network (520), a current sensing circuit (510), and a DC supply capacitance (502). The protection method (10) includes the steps of (a) providing a filament preheat period by initially setting the drive frequency at a first frequency, (b) shifting the drive frequency to a second frequency for igniting and operating the lamps, (c) changing the drive frequency back to the first frequency in response to a lamp fault, and (d) providing, upon correction of the lamp fault, a filament preheat period prior to attempting to ignite and operate the lamps.

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).