If a power supply could convert all of the power it’s receiving into usable power output, it would be 100% efficient. However, energy loss is an unavoidable part of energy-conversion systems, so a certain amount of energy is “lost” during each conversation stage as you convert from one voltage level to another. Typically, this is expressed as a percentage. A well-designed power supply can achieve efficiencies that approach the mid to high 90s.
The power supply should be as small as possible to save space or leave room for added system functions. To be truly useful, an integrated power and signal solution must not only offer high efficiency and high power delivery, but also high isolation performance and low emissions.