Overview

It is no surprise that power supplies get hot. Sometimes they get very hot. You have done everything you can do to maximize the efficiency in your design. Now you are faced with getting rid of the resulting heat energy.

Marketing will always want a switching power supply that costs zero, measures zero and is 100 percent efficient. You, as the power supply engineer, will just have to get used to not living up to the expectations of marketing.

The drive to further miniaturize electronics and the use of more and more surface mount packaging present a real challenge. The use of hot components that cannot be bolted to a heatsink means that more nontraditional methods of transporting heat away from these parts must be employed.

The rule of thumb in the reliability field is that, for every increase in 10 degrees Celsius of a component's temperature, its life is cut in half. So one's goal as a designer is to keep the component's temperature as low as possible to maximize the product life.

This chapter presents the mathematical method of modeling a thermal system and illustrates some approaches for the design of mechanical heatsinking assemblies. The author (me) presents the material in an understandable manner to help you through your design.

Marty Brown

Proper thermal design is essential to the overall design of a power supply. Overdissipation failures account for probably the largest portion of the failures. Therefore, it is essential that the designer understand its...