Abstract: A coaxial drop cable safety device is used for cable television, data and telephony applications. The device is used on buried drop cable where 60 Hz powering voltages applied to the drop cable exceed low voltage safety limits and where the drop cable is buried at depths which is less than the minimum required to meet electrical safety codes. Tap end and premise end units are connected to the drop cable. The tap end unit applies a DC voltage to the center conductor of the drop cable. A monitoring circuit in the tap end unit monitors the DC current in the center conductor. The tap unit will immediately remove the powering voltage in the event of either an open or faulted condition on the center conductor along the entire length of the drop cable. Additionally, while providing fault protection for the low frequency powering circuit due to tampering or damage to the cable, the fault monitoring circuit allows the high frequency television, data and telephony signals to pass with little or no impediment.

Abstract: A foldable transformer includes an enclosure (10), a plug assembly (12), and a locating assembly (14). The enclosure has a storage cavity (16) at a top end thereof. A window (20) is defined in the enclosure in communication with a bottom portion of the storage cavity, for receiving the plug assembly therethrough. The plug assembly includes a pair of inserting pins (34), a rotatable rod (36) having an arched profile, a pair of metal ears (38), and a pair spring pins (44). Each inserting pin is made of conductive material, is insert-molded in the rod, and electrically connects with a corresponding ear. The locating assembly includes a pair of slots (48) for receiving the spring pins, and a cam (56) for resiliently engaging with the plug assembly so that the plug assembly can be disengagably fixed in a folded position or an unfolded position.

Abstract: A converter circuit is specified for voltage maintenance in an electrical AC supply network (1), with the electrical AC supply network (1) having an associated voltage source (UR; US; UT) for each phase (R; S; T) for supplying an electrical load (2), with the converter circuit having a respective inverter (3) for each phase (R; S; T), which inverter (3) is connected on the DC side via an energy-storage capacitor (4) to a supply device (5). On the AC side, each inverter (3) is connected in series between the associated voltage source (UR; US; UT) and the electrical load (2) in the respective phase (R; S; T), and in that, on the AC side, the supply device (5) is connected to at least two phases (R; S; T) between the associated voltage sources (UR; US; UT) and the respective inverters (3).

Abstract: Method and apparatus are disclosed for providing a constant voltage, high frequency sinusoidal output across a varying load, using either a single or multiple switch topology operating at constant frequency while maintaining high efficiency over the entire load range. This embodiment is especially suited to applications which require the sinusoidal voltage be held very close to a desired value in the presence of rapid changes in the conductance of the load, even in the sub-microsecond time domain as is common in computer applications and the like and in powering electronics equipment, especially a distributed system and especially a system wherein low voltage at high current is required.

Abstract: An inverter apparatus includes an inverter circuit for driving a load. This inverter circuit has at least a pair of switching elements connected in series in a forward direction between both polarity terminals of a dc supply for supplying power to a load. An inverter drive circuit is employed for driving each switching element of the inverter circuit and has at least one high withstand voltage IC wherein the signal level reference potential is different in the input signal and the output signal. A clamping circuit clamps the potential of the low voltage side reference terminal, to which a potential, that is a reference for operation of the high withstand voltage IC in the inverter drive circuit and is a reference for a signal on the low potential side of the high withstand voltage IC, is applied. The voltage is clamped to the high voltage reference terminal to which is applied a reference potential for the high potential-side signal in the high withstand voltage IC.

Abstract: A reset circuit for deactivating a circuit configuration, which is fed by a supply voltage, in the case of an undervoltage supply. In this case, active components 1,2 (FIG. 1); or 3,2 (FIG. 3) are provided and their forward paths are connected in series between the supply voltage Uv and ground reference potential. The active components are fed directly or indirectly by a current mirror circuit 9 from a respective current source 10, 11. A reset signal Ureset (active=low signal) being present at the junction point 5 of the active components, where the junction point 5 is connected to ground reference potential via a resistor Rdown.

Abstract: A direct-current output voltage obtained by rectifying an alternating voltage generated in a secondary winding of an isolating converter transformer PIT is made constant using an active clamp circuit including an auxiliary switching device, a clamp capacitor, and a clamp diode connected in parallel with a parallel resonant capacitor supplied with the alternating voltage to step down and-make constant the direct-current output voltage without using a three-terminal regulator and a chopper regulator. A control circuit effects PWM control of the auxiliary switching device of the active clamp circuit and changes a capacitance of the parallel resonant capacitor. The direct-current output voltage is made constant, and a resulting power loss is reduced.

Abstract: A main-output circuit section includes a synchronous rectifying circuit composed of a NMOS, therefore, even if a load RL1 become light, a rise of direct current output voltage is prevented without a dummy resistor and electric dummy circuit, accordingly, when a NMOS is in an ON state, an abrupt narrowing of a time width does not occur. Therefore the product of voltage and time is ensured, direct current output voltage is easily produced stably.

Abstract: Zero voltage switching cells using a small magnetic circuit element, a pair of switches, and a capacitor are revealed. The application of the zero voltage switching cells to any of a wide variety of hard switching power converter topologies yields equivalent power converters with zero voltage switching properties, without the requirement that the magnetizing current in the main magnetic energy storage element be reversed during each switching cycle. The new switching cells either provide integral line filtering or a means to accomplish zero voltage switching with no high side switch drive mechanism. In the subject invention the energy required to drive the critical zero voltage switching transition is provided by the small magnetic circuit element, either a single winding choke or a two winding coupled choke, that forms part of the zero voltage switching cell. The application of the zero voltage switching cells to buck, buck boost, Cuk, flyback, and forward converters is shown.

Abstract: An inverter for generating ac power from a dc source includes an intermediate circuit with switches used to convert dc to ac and an output side with output chokes. Normally undesireable harmonics are generated in inverters. In the subject inverter, these harmonics are eliminated by providing a feedback from the output side to the intermediate circuit. The feedback includes a feedback choke inductively coupled to the output chokes.

Abstract: A primary winding T1 and a switching circuit 1 are serially inserted between input terminals Ti1 and Ti2 to which an alternating current is supplied. A diode 2, a resistor 3, and a capacitor 4 are serially inserted in parallel with the primary winding T1. A detecting circuit 5 is connected to both ends of the capacitor 4 and to an emitter and a collector of a phototransistor 7b. A control circuit 6 controls the switching circuit 1. A diode bridge 8 and a capacitor 9 are provided for a secondary winding T2. Output terminals To1 and To2 are connected to both ends of the capacitor 9. A voltage detecting circuit 10 is provided in parallel with the capacitor 9. The voltage detecting circuit 10 detects voltages which are outputted from the output terminals To1 and To2 and supplies the detected voltages to a control circuit 11. The control circuit 11 controls a light emitting diode 7a.

Abstract: This invention concerns a power supply voltage generator (1) for providing a second supply voltage (VDD2) for an electronic circuitry (60). A voltage converter (50) receives a first supply voltage (VDD1), and converts this into said second supply voltage (VDD2), such that its output voltage (VDD2) fluctuates in a control range between a lower limit (VLOW) and an upper limit (VHIGH). A voltage parameter source circuitry (3) generates a voltage parameter signal (VLOW) which is substantially equal to the minimum supply voltage value (Vmin) of the electronic circuitry (60), and feeds this voltage parameter signal (VLOW) to a parameter input (53) of the converter (50). The voltage parameter source circuitry (3) comprises a VCO (10) incorporated in a PLL. The voltage parameter signal (VLOW) is derived from a control signal (Vcontr) for the VCO (10).

Abstract: A primary winding (1) and a secondary winding (2) are layered concentrically with a magnetic substance forming a main magnetic circuit (13) and the magnetic resistance of a subordinate magnetic circuit (14) placed between the primary winding (1) and the secondary winding (2) is adjusted, whereby a concentric multilayer winding transformer having an arbitrary coupling coefficient can be provided.

Abstract: An apparatus for and method of achieving current balancing among phases of a multi-phase power supply by reducing and controlling the temperature variation among packages disposed within each phase. Each package contains a dc-to-dc converter (e.g. a buck converter), a temperature sensor and may also contain a driver, which supplies a pulse train for driving the converter. By controlling the temperature among phases to within ±X % a balancing of currents among phases to within ±X/2 % is achieved.

Abstract: A switched magamp post regulator in a power converter incorporating a switched set mode control circuit which minimizes the power loss associated with the control transistor of a set mode magamp post regulator is disclosed. Power loss in set mode is minimized by switching the control transistor on and off synchronously with the main transformer. The incorporation of set mode and switching allows the use of less expensive ferrite core materials with increased efficiency for operation at higher frequencies and higher temperatures.

Abstract: A high-accuracy linear amplifier is disclosed for sinking or sourcing current to or from a load. The linear amplifier includes input circuitry for receiving a predetermined input signal and rectifier circuitry. The rectifier circuitry is disposed at the output of the input circuitry and is operative in response to the input signal to generate a source/sink command signal. Output stage circuitry is coupled to the rectifier circuitry and includes a current sink transistor and a current source transistor. The output stage circuitry is responsive to the command signal to sink or source current through one of the respective transistors. The amplifier further includes feedback circuitry coupled between the output of the output stage circuitry and the input circuitry to provide an error signal for modifying the input signal. Bias circuitry maintains the non-conducting transistor in an on state during the sourcing or sinking of current.

Abstract: A single stage power factor correction circuit is disclosed. The circuit comprises a first comparator for receiving an output voltage and a reference voltage and for providing a control voltage, a multiplier coupled to the first comparator for receiving the control voltage and an input voltage and then providing a sine wave voltage and a control portion coupled to the multiplier for controlling the sine wave voltage and providing a regulated DC output. Through the use of the circuit in accordance with the present invention, circuit efficiency is increased and the number of circuitry components is reduced. By reducing the number of circuitry components a significant reduction in manufacturing costs is achieved.

Abstract: A power supply having a mixed regulator is able to provide the suitable power source according to the changing load by a switching mode voltage circuit and a series pass controlling circuit. The series pass controlling circuit has high sensitivity in detecting the changing the load, thus the power supply offers the suitable power source according to the changing of the load. The switching mode voltage circuit controls the transformer to output voltage by a PWM IC, so that the transistors for driving the transformer need not be powerful transistors which generate excessive heat. Thus a heat sink is not necessary and the power supply can accordingly be of a compact size.

Abstract: A current reference with reduced sensitivity to process variations includes two current sources. The first current source has an output current that is sensitive to process variations. The second current source has, as a component of its input current, the output current of the first current source. The input current to the second current source is substantially constant because the process dependent component has been removed by the output current of the first current source. Variable resistors internal to the current source are set using a control loop circuit and an external resistor.

Abstract: A serial circuit of the primary winding (21) of a transformer (2), a switching device (3) and a current-detecting resistor (4) is connected between a pair of dc terminals (18, 19). A smoothing capacitor (7) is connected to the secondary winding (22) of the transformer (2) via a diode (6). A resonance capacitor (5) is connected in parallel with the serial circuit of the switching device (3) and the current-detecting resistor (4). The current detection signal, the output voltage detection signal, and the switch voltage detection signal are combined to provide control pulses for the switching device (3). A control circuit (13) includes a minimum non-conducting period determination circuit for setting a first and a second minimum nonconducting period with hysteresis. The nonconducting periods of the switching device are placed under the limitation of the minimum nonconducting periods when the load is light.