Extracting Transformer Parameters

Steven M. Sandler, CTO, AEi Systems, LLC
   Danny Chow, Engineering Scientist, AEi Systems, LLC
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It is often the case, in circuits which use a transformer, that the performance of the circuit is significantly dependent on the characteristics of the transformer. This is true not only in power circuits but in the case of RF circuits as well. For example, a multi-output flyback power supply uses a coupled inductor as the "transformer." In this topology, the regulation, ripple, stability, and component stresses are all related to the magnitude, as well as the location of, the various leakage inductance terms, as well as, the mutual inductance of the transformer. This is a well-known documented concern; however, many transformer datasheets and specifications include only a single measurement for leakage and winding inductance.