Perhaps the most discussed figure-of-merit in any power supply conversation is efficiency. While it is true that efficient power conversion systems save on overall energy consumption, for many applications, the greater motivation behind an efficient design is the ability to reduce power losses in the system that manifest themselves as undesired sources of heat. Within the context of a small, enclosed power adapter, for example, the heat must be contained to provide a reliable system operation. This includes keeping the temperatures to an acceptable level on all components – from semiconductors to energy storage components such as inductors or capacitors. In inefficient power systems, high power losses can cause an excessive amount of mutual heating, which makes it almost impossible to dissipate heat without large heatsinks. In addition, commercial power adapters have external case temperature requirements that must be followed to provide safety and ease of use for the consumer. The smaller the enclosure becomes, containing the individual component temperatures becomes more difficult.

As the market continues to see the trend in miniaturizing these adapters, reducing power losses (or increasing the efficiency) becomes crucial to provide adequate thermal management within a small case. The fundamental problem is as follows - creating smaller power supplies requires better thermal management, and better thermal management requires higher efficiency of operation. With this in mind, if the objective is to create a small-form-factor design, the design question is not how can the highest efficiency be obtained? Instead the question is how can the required efficiency be obtained to create a thermally reliable design given the size requirements?