Abstract: A driver circuit or controller flexibly drives either a half-bridge or a full-bridge switching network in a backlight inverter without modification, redundant circuitry or additional components. The driver circuit includes four outputs to provide four respective driving signals that establish a periodic timing sequence using a zero-voltage switching technique for semiconductor switches in the switching network.

Abstract: A cold cathode fluorescent lamp controller exhibiting a multi-function terminal and operative alternately in a strike mode and a run mode, the controller comprising: a phase locked loop arranged for synchronization of an oscillator, associated with the controller, with an external signal, the phase locked loop comprising a capacitor coupled to the multi-function terminal; and a soft start circuit arranged to limit drive current immediately after reset of the controller responsive to a signal at the multi-function terminal. In one embodiment the controller further comprises an error detection circuit arranged to output an error signal on the multi-function terminal. In one embodiment the controller further comprises a frequency sweeping circuit operative to sweep the frequency of a drive signal during the strike mode of the controller, the frequency of the drive signal being swept by the frequency sweeping circuit responsive to a signal at the multi-function terminal.

Abstract: An apparatus and method for igniting a lamp during a strike mode of an inverter comprising: sequentially controlling a duty cycle sweep and a frequency sweep of driving signals in the inverter to provide an increasing output voltage to the lamp. One embodiment advantageously includes a closed feedback loop to implement the duty cycle sweep and the frequency sweep such that an open lamp voltage is reliably regulated during the strike mode. For example, the closed feedback loop stops the duty cycle sweep or the frequency sweep when the output voltage to the lamp reaches a predetermined threshold and makes adjustments to the duty cycle or frequency the driving signals as needed to keep the output voltage at approximately the predetermined threshold if the lamp has not ignited.

Abstract: A ring balancer comprising a plurality of balancing transformers facilitates current sharing in a multi-lamp backlight system. The balancing transformers have respective primary windings separately coupled in series with designated lamps and have respective secondary windings coupled together in a closed loop. The secondary windings conduct a common current and the respective primary windings conduct proportional currents to balance currents among the lamps. The ring balancer facilitates automatic lamp striking and the lamps can be advantageously driven by a common voltage source.

Abstract: An RF power transistor package with a rectangular ceramic base can house one or more dies affixed to an upper surface of the ceramic base. Source leads attached to the ceramic base extend from at least opposite sides of the rectangular base beneath a periphery of a non-conductive cover overlying the ceramic base. The cover includes recesses arranged to receive the one or more die, the ceramic base, gate and drain leads and a portion of the source leads. The cover further includes bolt holes arranged to clamp the ceramic base and source leads to a heat sink. Bosses at corners of the cover outward of the bolt holes exert a downward bowing force along the periphery of the cover between the bolt holes.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: Methods for forming a SiC BJT having a low base resistance and minimal emitter width are provided. The methods incorporate a plated shadow metal layer overhanging the emitter mesa. The mushroom-shaped shadow metal layer can then act as either a deposition shadow mask or an ion implantation mask in subsequent steps for forming base contacts. In this way, base contacts can be formed with a variable and controllable distance from the emitter mesa defined by the lateral extent of overhang of the shadow metal layer. The same shadow masking effect can also be used to form self-aligned emitter and base wiring metals for reduction of resistance. Plating of the emitter contact layer allows avoiding subsequent photolithography steps on the top of emitter mesa; thus emitter mesa width could be minimized.

Abstract: An apparatus and method for driving a lamp are provided. In one embodiment, an inverter having four switching elements is split into two inverter arms that are deployed at separate terminals of a floating lamp structure to achieve even light output. A controller drives both inverter arms such that power switching lines do not cross the floating lamp structure. In one embodiment, the controller adjusts the brightness of the lamp structure by adjusting the phase difference between outputs of a first inverter arm relative to a second inverter arm. In one embodiment, the controller adjusts the brightness by symmetrically pulse width modulating the outputs of the first inverter arm and the second inverter arm.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A solid state lighting unit constituted of: a control circuitry; a single string of light emitting diodes, the single string constituted of a plurality of sections each comprising a plurality of light emitting diodes; and a plurality of bypass paths each responsive to the control circuitry, each of the plurality of bypass paths arranged to provide bypass to a particular one of the plurality of sections, wherein the control circuitry is operative to identify an open circuit condition of a particular one of the plurality of sections, and activate the bypass path arranged to bypass the open circuit section, thereby providing light through sections not exhibiting an open circuit condition.

Abstract: A backlighting arrangement constituted of a driving transformer arrangement; a plurality of lamp pairs, each of the constituent lamps of the plurality of lamp pairs exhibiting a first electrical connection and a second electrical connection; and a plurality of balancing transformers, each comprising a primary winding and a secondary winding magnetically coupled to the primary winding, and each associated with a particular one of the plurality of lamp pairs, the primary winding of each of the plurality of balancing transformers serially connected between the second electrical connections of the constituent lamps of the associated lamp pair, the secondary windings of the plurality of balancing transformers serially connected in phase, with a first end of the serially connected secondary windings of the balancing transformers connected to one phase output of the driving transformer arrangement.

Abstract: A backlighting arrangement constituted of: a means for receiving an alternating current comprising a first lead and a second lead; at least one luminaire; and at least one first balancing transformer pair each associated with a particular one of the at least one luminaire, the primary of a first balancing transformer of the first balancing transformer pair serially coupled between the first lead of the means for receiving an alternating current and a first end of each of the at least one luminaire, and the primary of a second balancing transformer of the first balancing transformer pair serially coupled between the second lead of the means for receiving an alternating current and a second end of each of the at least one luminaires The secondaries of all of the at least one first balancing transformer pair are serially connected in a closed in-phase loop.

Abstract: A backlighting arrangement constituted of: a driving transformer; at least one balancing transformer; a plurality of luminaires, a first end of each of the plurality of luminaires connected to a high voltage lead of the driving transformer and a second end of each of the plurality of luminaires connected to a unique end of a winding of the at least one balancing transformer, wherein each pair of the luminaires is associated with a particular winding of one of the at least one balancing transformers, and wherein the first end and the second end of each of the luminaires is in physical proximity of the driving transformer and the at least one balancing transformer, the constituent lamps of the luminaires arranged in parallel and generally extending axially away from the proximity of the driving transformer.

Abstract: An apparatus and method for igniting a lamp during a strike mode of an inverter comprising: sequentially controlling a duty cycle sweep and a frequency sweep of driving signals in the inverter to provide an increasing output voltage to the lamp. One embodiment advantageously includes a closed feedback loop to implement the duty cycle sweep and the frequency sweep such that an open lamp voltage is reliably regulated during the strike mode. For example, the closed feedback loop stops the duty cycle sweep or the frequency sweep when the output voltage to the lamp reaches a predetermined threshold and makes adjustments to the duty cycle or frequency the driving signals as needed to keep the output voltage at approximately the predetermined threshold if the lamp has not ignited.

Abstract: An RF power transistor package with a rectangular ceramic base can house one or more dies affixed to an upper surface of the ceramic base. Source leads attached to the ceramic base extend from at least opposite sides of the rectangular base beneath a periphery of a non-conductive cover overlying the ceramic base. The cover includes recesses arranged to receive the one or more die, the ceramic base, gate and drain leads and a portion of the source leads. The cover further includes bolt holes arranged to clamp the ceramic base and source leads to a heat sink. Bosses at corners of the cover outward of the bolt holes exert a downward bowing force along the periphery of the cover between the bolt holes.

Abstract: A low voltage drop unidirectional electronic valve constituted of: a first terminal; a second terminal; an electronically controlled switch arranged to allow the flow of current from the first terminal to the second terminal when closed, the electronically controlled switch comprising a pair of reverse serially connected field effect transistors; a control circuit, arranged to close the electronically controlled switch responsive to the potential of the first terminal exceeding the potential of the second terminal by a predetermined amount; and a refresh circuit arranged to periodically open the electronically controlled switch. In one embodiment the low voltage drop unidirectional valve is arranged as one of a solar bypass element and an ORing diode.

Abstract: A secondary side voltage regulation scheme applied to a multiple output flyback converter. The output with the highest error voltage is selected to control the primary switch. The remaining outputs are regulated by varying the length of time that current is allowed to flow into each output by controlling the on time of a switch connected in series with each of the outputs. The switching of the windings is achieved using a single N channel MOSFET for each output. Regulation of the outputs is performed using leading edge modulation. The body diode of the output MOSFET switches are held off during the start of the commutation period by the use of an active clamp on the primary side.

Abstract: A ring balancer comprising a plurality of balancing transformers facilitates current sharing in a multi-lamp backlight system. The balancing transformers have respective primary windings separately coupled in series with designated lamps and have respective secondary windings coupled together in a closed loop. The secondary windings conduct a common current and the respective primary windings conduct proportional currents to balance currents among the lamps. The ring balancer facilitates automatic lamp striking and the lamps can be advantageously driven by a common voltage source.

Abstract: A backlight system drives multiple lamps using balanced groups of serially-connected lamp transformers. A plurality of lamp transformers is divided into multiple transformer groups. Primary windings of the lamp transformers are coupled in series in each transformer group. Lamps are coupled to secondary windings of the lamp transformers. The transformer groups are arranged in a parallel configuration. One or more balancing transformers couple the transformer groups to a common power source. The balancing transformers divide a common current from the common power source into multiple balanced currents for the respective transformer groups.

Abstract: A power conversion circuit operates in a discontinuous switching mode over a wide range of loading conditions and varies a coil peak current to maintain efficiency over the wide range of loading conditions. The coil peak current is adjustable based at least in part on a feedback signal generated in response to a load condition.