Abstract: There is provided a low-noise switching power supply for producing a regulated output voltage from an unregulated supply. The power supply includes a main transformer having first, second and third legs. A primary winding associated with a first leg produces an alternating magnetic flux in the core. A load winding associated with a second leg produces the output voltage from the power supply. A control winding is associated with the third leg. The regulated output voltage is compared to a reference voltage and used to operate a control circuit which alternately short circuits the control winding so as to vary the reluctance pass in the transformer and maintain the output voltage at a substantially constant predetermined value. A feedback circuit including a coupling transformer connects the primary coil to the switching circuit to improve regulation and provide a "soft start" capability.

Abstract: There is provided a low-noise switching power supply for producing a regulated output voltage from an unregulated supply. The power supply includes a main transformer having first, second and third legs. A primary winding associated with a first leg produces an alternating magnetic flux in the core. A load winding associated with a second leg produces the output voltage from the power supply. A control winding is associated with the third leg. The regulated output voltage is compared to a reference voltage and used to operate a control circuit which alternately short circuits the control winding so as to vary the reluctance pass in the transformer and maintain the output voltage at a substantially constant predetermined value. A feedback circuit including a coupling transformer connects the primary coil to the switching circuit to improve regulation and provide a "soft start" capability.

Abstract: A method and apparatus for providing uninterrupted DC and AC power for a desktop personal computer is described. The source of the uninterrrupted DC and AC power is derived from an integrated power supply that is sized to fit within the existing housings of most desktop personal computers as a plug-in replacement for existing power supplies. A high degree of efficiency is obtained using an integrated design with the main power conversion derived from a DC/DC dual primary resonant converter. The main primary of the resonant converter is driven from a high voltage DC bus which is supplied from AC mains when available. When the AC mains is unavailable, the second primary of the DC/DC dual primary resonant converter receives power from a low voltage battery source.