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Hi Experts,
My cusotmer want to evaluate the junction temperature of TPS7B69-Q1 on their PCB, so they glue a thermalcouple wire on the top of the package(without heat sink) and get the temperature Tc. In this application, which fomula should be used to calculate the junction temperature Tj? My understanding is the first one is more suitable here, right?
1. Tj = Tc+ψJT*Power
2. Tj = Tc+RθJC*Power
Hi Arie,
I would use the first equation unless a heat sink is being used in the application.
This App note can be used as a reference for the measurements you are making:
Semiconductor and IC Package Thermal Metrics.
Best,
Juliette
Hi Juliette,
Thanks for your reply. I also read this app note but still want to check with you, if using below setup to test the case temperature, we should use RθJC to calculate the junction temperature, right? Thank you.
Hi Arie,
If a heat sink is being used and the board is designed using JEDEC guidelines, you should use RθJC.
Best,
Juliette