Examples of Some Thermal Applications

These examples will show the reader a typical application of thermal analysis but with common application variations. These variations are useful in defining thermal boundaries within a design. 

1 Determine the Smallest Heatsink (or Maximum Allowed Thermal Resistance) for the Application 

This approach is useful for determining the smallest possible heatsink that an application can use before the thermal limit of a power device is exceeded. This is an example of a consumer market approach to designing a heatsink system. 

The device is an FDP6670 (Fairchild MOSFET) in a switching power supply. Convection cooling. 

Rearranging Equation A.l and solving for the thermal resistanee of the heatsink, 

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