TPSM33625: Thermal Measurement

Brian Wang0928

Genius 14030 points

Part Number: TPSM33625

Tool/software:

There're few questions about thermal measurements on control board in MD.

Since recommended TJ, max is specified as 125degree, customer would like to estimate TJ more precisely.

1. What's the difference between the thermal parameter 1 RθJC(top) and 2 (ΨJT) as red marked below diagram?

What parameter do you recommended to use? Why?

2. Since in the some cases, the thermal wiring is not easy to attach close to device as PCB size is slim and components is dense. Do you suggest to use parameter of RθJA (Junction to Ambient) for thermal estimation in practical? If so, where location putting the thermal wire measured point is more accurate for ambient temperature? Is there use guide for setup?

Using New Thermal Metrics.pdf

Regards

Brian

5 months ago

0 Rahil Ajani 5 months ago

TI__Genius 9460 points

Hi Brian,

This app note might help clear up some questions - https://www.ti.com/lit/pdf/spra953

Regards,

Rahil

0 Brian Wang0928 4 months ago in reply to Rahil Ajani

TI__Genius 14030 points

One more question.

For the question 2 as above, if RθJA is used for estimation of the junction temp, how to setup thermocouple wire correctly? is that close to DUT? What Is the distance in between? is there guidance for this measurement?

Regards

Brian

0 Rahil Ajani 4 months ago in reply to Brian Wang0928

TI__Genius 9460 points

Hi Brian,

Where you put the thermocouple for measuring ambient temperature is dependent on your environment. For example, in a thermal oven, anywhere inside the oven is okay.

There is no formal guidance. Just make sure it's not too close to IC to pick up heat from it.

Regards,

Rahil

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TPSM33625: Thermal Measurement