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ADRF6780 Junction Temperature Calculations

Question asked by KeithClark on Jun 27, 2018
Latest reply on Jun 28, 2018 by KeithClark


I am trying to calculate the maximum junction temperature of the ADRF6780 and seem to be making an error somewhere and wonder if someone could help clarify the problem?

From the ADRF6780 datasheet:-

Max Device Operating Temperature = +85 deg. C

Absolute Maximum Junction Temperature = 125 deg. C

Thermal resistance junction to ambient = 32.95 deg. C/W

Total Power Consumption (x2 LO, IF enabled) = 2.58 W

Assuming all the power is dissipated as heat (correct to first approximation)?


Junction temp. = Ambient temp. + (power dissipated x thermal resistance)

Therefore at the maximum device operating temperature the junction temperature will be:

Junction temperature = 85 + (2.58 x 32.95) deg. C

Junction temperature = 170 deg. C

This is 45 deg. C above the maximum allowable junction temperature?

My question is where am I going wrong?

Many thanks for any help you can offer.

Best regards

Keith Clark