Device Datasheets: Power Dissipation and How to Calculate Max Case Temperature

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Gathering Critical Data for use in Aavid Genie

Finding how much heat your electronic device dissipates and how to calculate max case temperature can sometimes be a pain. The device you are using in your application will typically have an extensive datasheet that accompanies your purchase or is available from the manufacturer. Most electronic device manufacturers are good about making this information available. Other times, you might need to chase down some of this information. You usually can find it from either the manufacturer or the vendor you purchased your devices from.

Terms You're Looking for in your Datasheet

Generally, these datasheets indicate: power dissipation (W), the maximum junction temperature (commonly °C), and a junction-to-case thermal resistance (generally °C/W) in the “Thermal” section. Hopefully the device manufacturer was kind enough to indicate where this block of information is in the table of contents or made it pop, since this information likes to hide away.

The Actual Math Part: Calculate Max Case Temperature

In order to calculate your maximum case temperature, first multiply the amount of heat the device dissipates by the junction-to-case thermal resistance to get the temperature rise from the junction to case. Then subtract this temperature rise from the maximum junction temperature to get the maximum case temperature.

Tjunction-max - (Ɵjunction-to-case*Pdissipated) = Tcase-max

In some cases, figuring out what your datasheet is saying can be a trying ordeal. Thermoelectric Coolers (TECs) or Thermoelectric Devices (TEDs) can be doubling confusing since there is a "hot side" and a "cold side," and the control of both sides is critical to function.

If All Else Fails

If you need assistance, please don’t hesitate to contact our Aavid Design Engineers. They’ve had extensive experience in reading these types of datasheets and help you design the right solution for you.

Have questions?