Sinrace Power Supply Technology (Shenzhen) Co., Ltd.

Power efficiency is a fundamental characteristic of any switch-mode power supply (SMPS), and its measure generally dictates the quality of the conversion device. High numbers bestow bragging rights upon the successful engineer, while low numbers usually denote the need for modification or redesign.

Maximum efficiency is a prime consideration for all SMPSs, but even more so for those found in portable devices, where battery life must be prolonged to offer consumers extended run time while using their favorite gadgets and toys. High efficiency is also a must for those designs that require improved thermal management, or where the cost of providing power is of concern.

To achieve the maximum conversion efficiency in an SMPS design, the engineer must understand the elementary power-loss mechanisms inherent in these converters, and what can be done to mitigate their effects. Additionally, familiarity with common SMPS IC features that facilitate higher efficiency enable the engineer to make better choices when confronted with switch-mode converter design.

In this two-part discussion, the basic factors affecting SMPS efficiency are explained and guidance is provided on how to start a new design. Introductory material and switching component power losses are covered in this first installment.