Abstract: The invention involves a method of packaging and interconnecting four power transistor dies to operate at a first frequency without oscillation at a second frequency higher than the first frequency but lower than a cutoff frequency of the transistors. The dies are mounted on a substrate with a lower side (drain) of each die electrically and thermally bonded to a first area of a conductive layer on the substrate. A source of each die is electrically connected to a second area of the conductive layer on the substrate. A gate of each die is electrically connected to a third, common interior central area of the conductive layer on the substrate via separate electrical leads.

Abstract: An LED backlighting system including: a control circuit; a power source; at least one LED string associated with the power source, the at least one LED string being arranged to be switchably connected to alternatively draw an illumination current from the power source and not draw an illumination current from the power source; and a controlled bleeder arranged to draw a bleed current from the power source responsive to the control circuit; the control circuit being operative to draw the bleed current from the power source via the controlled bleeder for a predetermined time period associated with the alternatively drawing and not drawing the illumination current of the at least one LED string.

Abstract: A lamp inverter with continuous strike voltage facilitates faster striking of a fluorescent lamp, especially at cold temperatures. A frequency sweep generator sweeps the frequency of the lamp inverter to a striking frequency corresponding to a striking lamp voltage and then maintains the striking frequency until the lamp strikes.

Abstract: A backlighting system comprising: a color manager; a plurality of luminaires, each of the luminaires comprising a LED string and arranged to illuminate a particular portion of a display associated therewith; a color sensor arrange to receive light from one of the luminaires; and a plurality of thermal sensors each associated with a particular luminaire and in communication with the color manager, the plurality of thermal sensors being less than the plurality of luminaires, the color manager, responsive to the plurality of thermal sensors and the color sensor, being operable to calculate color coordinates for each of the plurality of luminaires.

Abstract: A power conversion circuit improves lamp operating life and lamp efficiency by driving a fluorescent lamp with a square wave signal. The square wave signal is an alternating current signal with relatively fast transition times. The square wave signal advantageously reduces lamp current crest factor for more efficient operation of the fluorescent lamp.

Abstract: A shoot-through prevention circuit is used in a power conversion circuit that uses a passive level-shifter to drive a P-type transistor in a switching network. The shoot-through prevention circuit is coupled between a controller output that provides a driving signal to control the P-type transistor and the passive level-shifter coupled to a control terminal of the P-type transistor. The shoot-through prevention circuit couples the controller output to the passive level-shifter when the driving signal has a first logic level associated with turning on the P-type transistor and isolates the controller output from the passive level-shifter when the driving signal has a second logic level associated with turning off the P-type transistor.

Abstract: A system and method for power over Ethernet comprising: a plurality of power over Ethernet supplying ports; and a management station in communication with each of the plurality of power over Ethernet supplying ports, the management station being operative to: disable at least one first power over Ethernet supplying port of the plurality of power over Ethernet supplying ports on a predetermined scheduled basis. Preferably the management station is further operative to: receive an entry indication; and enable the disabled at least one first power over Ethernet supplying port responsive to the received entry indication.

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 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: High voltage switches are configured with a junction transistor driven with a transformer coupled AC drive signal in the common base configuration or driven by a capacitor coupled charge pump. The high voltage switches may be configured as half wave or full wave switches wherein the junction transistor is driven during one or both half cycles of the AC drive signal. Bipolar switches that can stand off high DC voltage of either polarity, or that can stand off high AC voltage, are configured from two junction transistors with their bases connected and their emitters connected. These switches may also be driven in full wave or half wave mode, by a transformer or by single or dual capacitive charge pumps. Either NPN or PNP transistors may be used. Example drive circuits, which can be constructed as low voltage integrated circuits, are given for all of the switch types.

Abstract: A lamp inverter with continuous strike voltage facilitates faster striking of a fluorescent lamp, especially at cold temperatures. A frequency sweep generator sweeps the frequency of the lamp inverter to a striking frequency corresponding to a striking lamp voltage and then maintains the striking frequency until the lamp strikes.

Abstract: An apparatus and methods for balancing current in multiple negative impedance gas discharge lamp loads. Embodiments advantageously include balancing transformer configurations that are relatively cost-effective, reliable, efficient, and good performing. Embodiments include configurations that are applicable to any number of gas discharge tubes, such as cold cathode fluorescent lamps. The balancing transformer configuration techniques permit a relatively small number of power inverters, such as one power inverter, to power multiple lamps in parallel. One embodiment of a balancing transformer includes a safety winding which can be used to protect the balancing transformer in the event of a lamp failure and can be used to provide an indication of a failed lamp.

Abstract: A method for preventing an excess voltage from appearing at an output of a power over Ethernet controller, the method comprising: sensing that a powered device has been disconnected from a port; enabling a bypass path around a means for unidirectional current flow operatively connected to the port; and disconnecting power to the port responsive to the sensed disconnect, whereby the bypass path enables a discharge path for an output capacitor present across the port. The invention also provides for a circuit having a bypass path around a means for unidirectional current flow, the bypass path being enabled by a control circuit to prevent an excess voltage from appearing at a sensing input of the control circuit. In an exemplary embodiment the bypass path is enabled approximately simultaneously with disconnecting power from the output port.

Abstract: A system for location identification in a local area network comprising: a current limited voltage source; a telecommunications outlet; communication cabling connecting the current limited voltage source to the telecommunications outlet; and a location identifier associated with the telecommunications outlet, the location identifier being responsive to a pre-determined voltage level from the current limited voltage source to transmit a multi-bit location data. In one embodiment the multi-bit location data is received at the power sourcing equipment and in another embodiment the multi-bit location data is received at a data terminal equipment connected to the telecommunications outlet.

Abstract: An efficient and flexible current-mode driver delivers power to one or more light sources in a backlight system. In one application, the current-mode driver is configured as an inverter with an input current regulator, a non-resonant polarity-switching network, and a closely-coupled output transformer. The input current regulator can output a regulated current source in a variety of programmable wave shapes. The current-mode driver may further include a rectifier circuit and a second polarity-switching network between the closely-coupled output transformer and a lamp load. In another application, the current-mode driver delivers power to a plurality of light sources in substantially one polarity by providing a regulated current to a network of time-sharing semiconductor switches coupled in series with different light sources coupled across each semiconductor switch.

Abstract: A system for powering and controlling an LED backlight, the system comprising: a control circuitry; a plurality of LED strings; a pulse width modulation functionality associated with the control circuitry and arranged to pulse width modulate a current flow through each of the plurality of LED strings; and a plurality of current limiters responsive to the control circuitry, each of the plurality of current limiters being associated with a particular one of the plurality of LED strings and operative to limit current flow of the pulse width modulated current there-through, the control circuitry being operative in the event of a thermal condition of one of the plurality of current limiters to reduce a duty cycle of the pulse width modulation functionality of the current flow through the one of the plurality of current limiters.

Abstract: A system for powering and controlling an LED backlight, the system comprising: a control circuitry; a controllable power source responsive to the control circuitry; and a plurality of LED strings receiving power from the controllable power source, the control circuitry being operative to control the output voltage of the controllable power source responsive to a function of an electrical characteristic of at least one of the plurality of LED strings.

Abstract: A high density device comprising: a chassis frame configured and dimensioned for mounting in a standardized telecommunications rack, the chassis frame defining a front plane and a back plane, the front plane being substantially coincident with a front support of the telecommunications rack; a sub-module chassis secured to the chassis frame, the sub-module chassis exhibiting a proximal face and a distal face; a first plurality of jacks located distal of the proximal face of the sub-module chassis; and a passageway formed between the sub-module chassis and an inner wall of the chassis frame, the passageway configured and dimensioned for the passage of cabling for connection to the first plurality of jacks.

Abstract: A method of power management for use in a local area network, in which a plurality of local area network nodes are supplied power over communication cabling, the method comprising: supplying power to the plurality of local area network nodes over communication cabling; inputting total power availability; monitoring total power consumption; establishing a first limit for the monitored total power consumption; establishing a second limit for the monitored total power consumption, the second limit being lower than the first limit; in the event the first limit is exceeded, disconnecting the supplied power to at least one of the plurality of local area network nodes; and in the event the second limit is exceeded, supplying power to an additional node only after disconnecting the supplied power to at least one of the plurality of local area network nodes.

Abstract: This invention discloses a local area network including a hub, a plurality of nodes, communication cabling connecting the plurality of nodes to the hub for providing data communication, and a power supply distributor operative to provide at least some operating power to at least some of the plurality of nodes via the communication cabling.