Abstract: A circuit device and method for protecting EMC components from fault conditions that may negatively affect the components, such as high power dissipation in EMC components when/if the boost stage stops working or malfunctions and preventing smoke and fire in case the boost stage switching device fails, shorts, or is defective. The device is designed so that the chopper stage (following the boost stage) is latched off if/whenever the boost stage stops working. According to the methods of the invention, whenever such a fault occurs at the boost stage, the circuit immediately disables the stage that provides power to the output load (i.e., load-power-supply stage). This disabling of the load-power-supply stage then prevents very high currents from flowing through the EMC components and thus protects the EMC components from overheating and/or causing a fire or smoke.

Abstract: An AC adapter which reduces the amount of power drawn from an AC power source when a system is disconnected from the adapter, includes: a rectifier bridge for rectifying an AC voltage from an AC power supply; a conversion circuit coupled to the rectifier bridge for converting the rectified AC voltage to a DC voltage; and an opto-coupler coupled to the conversion circuit for monitoring an output connection of the circuit, wherein when a system is not coupled to the output connection, the opto-coupler substantially prevents the AC voltage from being drawn from the AC power supply. The adapter circuit uses an opto-coupler comprising a diode and a transistor to reduce the amount of current drawn from an AC power supply when a system is not connected to the AC adapter. In this manner, the AC adapter is prevented from becoming heated when no system is connected.

Abstract: Aspects of a fail safe circuit for protecting power supply operation from a failure are described. The fail safe circuit shutdowns at least one power supply when a preset threshold is exceeded and resets to resume normal operation following a temporary fault condition. The fail safe circuit includes a switch coupled to a voltage signal line of a branch of a power supply system, a current sense resistor coupled to the switch for detecting a failure condition in the branch, and a latch coupled to the current sense resistor and the switch for turning the switch off during the failure condition.

Abstract: Aspects for integrating speed control and fault detection in a fan assembly are described. The aspects include a fan, a first circuit is coupled to the fan for regulating speed of the fan, and a second circuit coupled to the fan and to the first circuit for detecting a fault condition in the fan. A ripple regulator is integrated as the first circuit, and a pulse missing detector circuit is integrated as the second circuit.

Abstract: A power factor correction circuit is disclosed. The power factor correction circuit comprises a converter portion, a boost stage portion coupled to the converter portion, and an energy reserve portion coupled to the boost stage portion, the energy reserve portion for providing a voltage for the power factor correction circuit in the event of an interruption of power to the circuit. Through the use of the circuit in accordance with the present invention, the use of expensive, higher rated circuitry components is avoided. By avoiding the use of expensive higher rated circuitry components a significant reduction in manufacturing costs is achieved.

Abstract: An AC adapter which reduces the amount of power drawn from an AC power source when a system is disconnected from the adapter, includes: a rectifier bridge for rectifying an AC voltage from an AC power supply; a conversion circuit coupled to the rectifier bridge for converting the rectified AC voltage to a DC voltage; and an opto-coupler coupled to the conversion circuit for monitoring an output connection of the circuit, wherein when a system is not coupled to the output connection, the opto-coupler substantially prevents the AC voltage from being drawn from the AC power supply. The adapter circuit uses an opto-coupler comprising a diode and a transistor to reduce the amount of current drawn from an AC power supply when a system is not connected to the AC adapter. In this manner, the AC adapter is prevented from becoming heated when no system is connected.

Abstract: A power supply system for providing power to a load is disclosed. The power supply system comprises a plurality of sources and a plurality of power supplies. Each of the plurality of power supplies has an input and an output. Each of the plurality of power supplies are coupled to one of the plurality of sources. One of the plurality of power supplies provides a power status signal. The outputs of the plurality of power supplies are coupled together. The power supply system includes a switching circuit coupled to the plurality of sources and receives the power status signal. The power supply system further includes a back up power supply. The back up power supply has an input and an output. The input of the back up power supply is coupled to the switching circuit. The output of the back up power supply is coupled to the output of the plurality of power supplies. The switching circuit monitors the power status signal and switches in the back up power supply when a power interruption occurs.

Abstract: A power converter circuit is disclosed. The power converter circuit comprises an oscillator for receiving an input wherein the oscillator operates with a fixed frequency and a resonant circuit coupled to the oscillator, wherein the resonant circuit is adjusted to minimize switching losses. Through the use the power converter circuit in accordance with the present invention, high switching losses are avoided thereby resulting in an increase in the overall efficiency of the power converter circuit.

Abstract: Aspects of failure detection of an isolation device in a power supply of a redundant power supply system are described. The aspects include an isolation device coupled to a voltage input line of a power supply. A comparator coupled to the isolation device provides a predictive failure analysis (PFA) signal when the isolation device fails.

Abstract: The present invention provides a highly efficient power supply with redundant multiple input voltage sources. The power supply uses switching transistors, specifically MOSFET's, to create paths for current from one of the voltage sources to the load. The switching transistors are switched either “on” or “off” by comparators which compare the output from the voltage sources. These comparators allow the highest voltage source to provide power to the load, and keep the other switching transistors “off” that connect the common load to other voltage sources. Because the switching transistors have lower conduction losses than diodes in conventional power supplies, the power supply in accordance with the present invention is more efficient.

Abstract: Aspects for a power converter with power factor correction (PFC) circuit are described. The aspects include a buck/boost circuit for achieving a DC voltage from an AC input voltage signal line without developing an inrush current from the AC input voltage line, and a DC/DC converter circuit coupled to the buck/boost circuit for converting the DC voltage to a desired voltage level. The aspects are achieved in a straightforward, cost effective, and adaptable manner.

Abstract: A multiphase zero-volt switching, zero volt switch resonant DC-DC regulator includes: a zero-volt switch zero volt switch; a DC output voltage means; a variable resonant circuit; a synchronous rectifier; and a sensing circuit. The sensing circuit senses a DC output voltage at the DC output of the regulator. The regulator uses the resonant circuit in conjunction with the sensing circuit to provide a substantially constant DC output voltage at a fixed frequency. If the sensing circuit senses a change in the DC output voltage, then a resonant frequency of the regulator is changed by the variable resonant circuit. This allows the oscillator of the regulator to maintain a fixed frequency, thus ensuring the availability of zero-volt switching over the full range of operation. The regulator also has the advantages of low power loss, reduced ripple, and a very fast transient response time.

Abstract: A power supply system for providing power to a load is disclosed. The power supply system comprises a plurality of sources and a plurality of power supplies. Each of the plurality of power supplies has an input and an output. Each of the plurality of power supplies are coupled to one of the plurality of sources. One of the plurality of power supplies provides a power status signal. The outputs of the plurality of power supplies are coupled together. The power supply system includes a switching circuit coupled to the plurality of sources and receives the power status signal. The power supply system further includes a back up power supply. The back up power supply has an input and an output. The input of the back up power supply is coupled to the switching circuit. The output of the back up power supply is coupled to the output of the plurality of power supplies. The switching circuit monitors the power status signal and switches in the back up power supply when a power interruption occurs.

Abstract: The present invention provides an adapter circuit which improves efficiency and size. The adapter circuit includes: a selective voltage doubler which approximately doubles an input voltage with a low line connector and does not with a high line connector; a switcher coupled to the selective voltage doubler; a resonant circuit coupled to the switcher; a first diode and a second diode coupled to the resonant circuit; and a filter coupled to the first and second diodes. When a low line connector is used, the input voltage is doubled and a one diode drop is used. When a high line connector is used, the input voltage is not doubled and a two diode drop is used. This allows the adapter circuit to be significantly reduced in size and weight. It also has low power loss.

Abstract: An adapter circuit in power supplies utilizes a selective voltage doubler which approximately doubles an input voltage with a low line connector and does not with a high line connector. The selective voltage doubler is coupled to a switcher, which in turn is coupled to a resonant circuit. The resonant circuit is coupled to a first diode and a second diode and a filter. When a low line connector is used, the input voltage is doubled and a one diode drop is used. When a high line connector is used, the input voltage is not doubled and a two diode drop is used.

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 circuit for limiting inrush current to a power source is disclosed. The circuit includes a low voltage drop semiconductor device coupled to the power source and a resistor coupled in parallel with the low voltage drop semiconductor device. The circuit further includes a diode coupled in parallel with the resistor and an AC detector coupled to the low drop semiconductor device. The AC detector controls the low voltage drop semiconductor device in a manner such that when power is applied to the power source the inrush current to the power source is minimized. The low voltage drop semiconductor device is utilized in conjunction with an AC detector to simultaneously reduce transistor power dissipation and reduce the detrimental effects of inrush current. By reducing the transistor power dissipation as well as the detrimental effects of inrush current, a significant improvement in the overall efficiency of the circuit is achieved.

Abstract: A high efficiency power converter and method of operation thereof. The high efficiency power converter includes a preregulator circuit that provides a regulated intermediate DC voltage to a low impedance output stage. The low impedance output stage includes first and second power transformers, where each of the power transformers has first and second primary windings of opposite polarity and a secondary winding. The low impedance output stage also includes first and second switches that alternatively couple the first primary windings of the first and second power transformers, respectively, to the regulated intermediate DC voltage. The low impedance output stage further includes first and second coupling capacitors that couple the second primary windings of the first and second power transformers to the second and first switches, respectively, and are utilized to reset the first and second power transformers with minimum losses.

Abstract: A multiple output power supply circuit is disclosed. The power supply circuit comprises an input voltage wherein the input voltage is coupled to a driver and a transformer coupled to the input voltage wherein the transformer is coupled to at least one switch. The power supply circuit further comprises at least two rectifiers, each of the at least two rectifiers coupled to the transformer via a winding, each of the at least two rectifiers comprising at least one diode and a controlled switching device coupled in parallel. According to the present invention, the circuit in accordance with the present invention provides multiple power outputs in a substantially more efficient manner.

Abstract: Aspects for a power converter with power factor correction (PFC) circuit are described. The aspects include a buck/boost circuit for achieving a DC voltage from an AC input voltage signal line without developing an inrush current from the AC input voltage line, and a DC/DC converter circuit coupled to the buck/boost circuit for converting the DC voltage to a desired voltage level. The aspects are achieved in a straightforward, cost effective, and adaptable manner.