Overview and Basic Terminology

Any regulator carries out the process of power conversion with an efficiency, defined as 

Iin is the average or dc current being drawn from the source. 

Ideally we want r) = 1, and that would represent a perfect conversion efficiency of 100%. But in a real converter, that is with t 1, the difference Pin — Po is simply the wasted power Pioss, or dissipation (occurring within the converter itself). By simple manipulation we get 

This is the loss expressed in terms of the output power. In terms of the input power we would similarly get 

The loss manifests itself as heat in the converter, which in turn causes a certain measurable temperature rise AT over the surrounding room temperature (or ambient temperature ). Note that high temperatures affect the reliability of all systems — the rule-of-thumb being that every 10°C rise causes the failure rate to double. Therefore, part of our skill as designers is to reduce this temperature rise, and thereby also achieve higher efficiencies. 

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