Unitrode Power Supply Design Seminar Design Review

50W Forward Converter with Synchronous Rectification and Secondary Side Control	This topic reviews a new technique for secondary side control of a DC-DC converter without using an external bias supply. A unique primary side startup circuit is used to drive the primary side power transistor. Gate pulse information for the primary transistor is transmitted through a pulse edge transformer that is shown to be smaller than an optoisolator. The discussion includes transformer-reset technique, pulse edge transmission circuit design and forward converter design procedure. The converter startup transient and control hand-off are explained in detail. Experimental results include operating waveforms, startup waveforms, and efficiency.
Unique Cascaded Power Converter Topology For High Current Low Output Voltage Applications	High current, low output voltage applications emerge daily with the introduction of new generation microprocessors and data communication systems. Most recent applications also require multiple, isolated, independently controllable outputs with tight voltage regulation. The focus of this design review is a new cascaded power converter topology especially suitable for modular, low cost, high frequency converters addressing this most recent power conversion need. The presentation includes the operating principles, design trade-offs and critical steps of design procedure. Measurement results from a 48V to 1.5V, 20A output power supply to complement the paper.
Introduction to Hot Swap Power Management	This topic introduces the concept of Hot Swap power busses and why hotswapping is becom-ing a mainstream requirement, particularly in the telecommunications industry. Several methods of implementing hot swap will be provided along with the pros and cons of each method. Finally a hot swap design utilizing an intelligent Hot Swap Power Manager™ IC from Unitrode will be presented for a typical -48V telecom application.
Power Supply Components	A survey of Unitrode products suitable for switching power supply applications is presented, with emphasis on recently introduced products.
400W Single-Stage Current-Fed Isolated Boost Converter with PFC	This paper will detail the operation and design of current-fed isolated boost converters for PFC applications. Theory of operation will be explained and comparative analysis of the current-fed push-pull and full bridge converters will be provided. In addition, a detailed design procedure will be developed and an example design worked through. The targeted application is a 400W, universal AC input to 42V DC output voltage power factor corrected power supply.
Inductor and Flyback Transformer Design	This topic builds upon and completes the Magnetics Design topic presented at Unitrode Seminar, SEM1200, 1997-98. A design approach is presented which optimizes utilization of the magnetic core, thereby minimizing size and cost. Core and winding losses can range from insignificant to catastrophic depending upon the nature of the application and the operating current mode. The design approach is illustrated with cookbook examples of a buck filter inductor, a flyback transformer for continuous current mode operation, and a discontinuous mode flyback transformer. An updated Magnetics Design Handbook including reference articles will be provided to each seminar attendee.