Abstract: An electronic method and apparatus are described for an isolated, universal input, power supply in the form of a single-ended resonant converter that utilizes capacitive energy storage versus magnetic energy storage, for converting an ac or DC input voltage to a variable voltage and current DC output or a variable ac output voltage, current, frequency, or phase. The preferred topology is a direct ac to ac, single-ended resonant converter using a single switch (4) and integrated magnetic element (1) with inherent near-unity power factor. Advantages of this method include a significant reduction in global energy consumption, simpler circuitry, substantially lower cost, higher efficiency, and longer operational life.

Abstract: An all-ranging DC output uninterruptible switched mode power supply (SMPS) of off-line flyback topology is capable of operating with an input voltage between 90 v AC and 270 v AC and an input frequency range of 40 Hz-70 Hz for operation throughout the world. Provided with a battery backup, the SMPS gives DC output without interruption even during AC power failures. The battery and the regulated AC main's supply outlet are connected through an "OR" connection comprising Shortsky rectifier diodes. A pulse width modulator whose conductive duty cycle is responsive to the condition of a voltage, Vcc, provides a reference voltage. An isolated flyback converter includes MOSFET transistor switch and power transformer. The power transformer stores energy in its primary winding when transistor is conductive and transfers energy to the secondary winding when transistor is nonconductive. The pulse width modulator controls the conduction of the transistor.