International Business Machines Corporation

Robert J Huljak

Donald Wayne Stafford

Bruce M Cassidy

Stephen F Newton

Kenneth Andrew Wallace

Arthur E Graham

Deh C Tao

Patsy A Bowlds

A DC to DC power converter having reduced switching loss for operation at high frequencies. As disclosed, a buck, or forward, converter includes a first FET as the switching device in series with an inductor and a second FET as the flywheel device. At the common node to which the two FET's and the inductor are connected, there is sufficient capacitance that the FET's may be turned off without appreciable voltage change across the FET's. The value of the inductor is chosen, with respect to the input and output voltages and frequencies of operation involved, to insure that the inductor current polarity reverses each cycle, raising the node voltage to the level of the input voltage, substantially eliminating turn-on losses of the first FET. Control circuitry is provided for regulation of the power converter to control the peak-to-peak current in the inductor and to insure that at least a selected minimum value of the inductor current is present for each cycle of operation of the converter. An over-voltage protection circuit for the output of the converter is also provided.

FET power converter with reduced switching loss

Disclosed is a thermal transfer medium which comprises a mixture of a thermosetting polyimide, a thermoplastic polyimide, and graphite. It has a steel support layer and an intermediate layer of silicon dioxide. An outer layer on the steel is the thermal ink. The mixture is applied as a dispersion with a precursor of the thermosetting polyimide. The ribbon may be recoated at the typing station by applying a hot-melt of the ink.

Silicon dioxide intermediate layer in thermal transfer medium

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Lexington, KY, United States of America

Robert J Huljak