What is the Rthjc ( junction to case thermal resistance) for MC_S9S08RN32W1VLC, LQFP32-R?

[nishantpandey]

I have evaluated my microcontroller @ 85 deg C & I want to calculate the junction temperature of micro controller.

For this i need junction to case thermal resistance.

Also if i keep microcontroller  ON for 1000hr on 85 deg C then will it sustain this?

Currently at 85deg C measured case temperature is 96.9 deg C.

[john_suchyta]

Hi Nishant,

Since our 8-bit MCUs are generally used without heatsinks, we do not specify junction to case thermal resistance. We specify the junction to ambient thermal resistance. Measuring the case temperature will not tell you the die temperature. The only way you can estimate die temp is measure the power dissipation (internal and external) at the ambient you choose and multiply that by either of the 2 Theta JA values in the datasheet. Typically, users estimate the power consumption of their circuits and verify that with measurements if the die temp is critical.

Note that we run accelerated life test stresses for 1008 hours at an ambient temperature greater than the maximum junction temperature (135 deg C for RN family).

Regards,

John Suchyta