Understanding Datasheet Thermal Parameters and IC Junction Temperatures
There is much confusion regarding how to make meaningful design decisions when converting a datasheet’s thermal resistance parameters. This introductory article will help today’s hardware engineers understand how to decipher the thermal parameters found in datasheets — including whether to choose theta vs. psi, how to calculate these values, and most importantly, how to apply these values to a design in a practical manner. This article will also describe the relationship between application ambient temperatures, and how they compare to PCB temperatures or IC junction temperatures. Lastly, it will discuss how power dissipation changes with temperature, and how to use this characteristic to achieve a cool-running, cost-optimized solution. Electrothermal Analogy - To understand thermal quantities more easily, there are certain analogies that can be made between thermal and electrical quantities.