Hi,

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)?

Then

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

Hello Keith,

You are correct, your equation is right and the numbers that you used are correct.

We have a mistake in the data sheet. The thermal resistance junction to ambient is 9.18C/W and not 32.95 deg C/W as say in the data sheet.

I will correct it

Thank you for let us know.

Assaf