TPS7B69-Q1: Junction temperature calculation

Arie Li

Part Number: TPS7B69-Q1

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

over 2 years ago

0 Juliette over 2 years ago

TI__Genius 16606 points

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

0 Arie Li over 2 years ago in reply to Juliette

TI__Expert 3390 points

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.

0 Juliette over 2 years ago in reply to Arie Li

TI__Genius 16606 points

Hi Arie,

If a heat sink is being used and the board is designed using JEDEC guidelines, you should use RθJC.

Best,

Juliette

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TPS7B69-Q1: Junction temperature calculation