Don't Be Misled by Power Device Specs
by Roger Stout, Senior Research Scientist, ON Semiconductor, Technology Development, Advanced Packaging, Phoenix, Power Electronics Technology, May 01 2008
Focus:
Datasheet specifications for maximum power dissipation for a power semiconductor device
can be confusing. For a given device in a given package, sometimes more than one value of
maximum power is specified, and the test conditions under which those ratings were
obtained are not clearly explained. Some engineers are left wondering what the maximum
power rating is for a given package. But as the author explains in this article, the
maximum power rating largely depends on external factors in the application such as
ambient temperature, the heat contribution from other heat sources, and the thermal
resistance from package to ambient. All of these factors combine with the package
dependent portion of thermal resistance to determine the maximum power dissipation for a
given device. The author explains all this using simple electrical analogies and graphs to
illustrate the concepts. Then, he presents a datasheet example to further illustrate how
there can be two maximum power ratings for a given device without contradiction.
What you’ll learn:
- How to understand and interpret power device ratings given on datasheets
- How to determine the maximum power dissipation for a power semiconductor device
Notes:
A PDF of the article as it appeared in print is available at
http://powerelectronics.com/thermal_management/
thermal_management_simulation/805PET21pow
er-device-speed.pdf
View this Source (requires a PDF Viewer installed on your device)
© 2025 How2Power. All rights reserved.