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elessargr , 08-30-2025, 01:26 PM

Hello to all,
hope everyone goes well.

I would like to ask a quick question if anyone is aware.
I am working with the TUSB8020B (TUSB8020BIPHPRQ1) which I am using it as a 2x port HUB. From the moment I am connecting it to the USB port the IC in less than 1sec gets extremely hot.
With a thermal camera the IC shows 60C. Yes the IC is designed to be okay at that temperature but I am not sure if it should be reaching this without any load on it and especially in 1sec from the moment its energized.

Is this normal?

On the PCB yes I have some vias for thermal relief (4) but something seems off.

To clarify I am still learning when it comes to electronic schematic design and PCBs.

Any recommendations, ideas are welcome in order to figure out what causes this if its not expected.

Thanks again!

Sniper2 , 08-30-2025, 05:00 PM

pcb picture?

elessargr , 08-30-2025, 06:15 PM

I assume you mean those?

elessargr , 08-30-2025, 06:16 PM

the two middle layers are ground and power. So nothing much to show

FuzzyOtter , 08-31-2025, 02:10 AM

Any reason you didn't follow the recommended footprint shown in the datasheet? It shows a significantly larger area of copper placed under the thermal pad of the IC, with more vias. You also have vias running under the chip where TI recommends the thermal pad should be. Are your vias tented? Is the "thermal pad" solder shorting against any of those vias?

Robert Feranec , 08-31-2025, 02:42 AM

if it gets hot in less than 1s that looks like something is wrong. measure currents and voltages going into the chip

elessargr , 08-31-2025, 09:45 AM

good morning!
Thank you both for those details/suggestions!!

elessargr , 08-31-2025, 09:46 AM

FuzzyOtter tbh I didnt see that picture all those months now in the datasheet until you mentioned it. I was always going until page 37/38 where I thought the datasheet ended. I was wrong 🙁
Definitely the vias are not tented.
On my new design (attached) I placed more vias and now I think I would place even more. Not sure if there is a way to remove vias and make it a solid piece through all layers as copper or something like that. Need to check.
I dont believe there is a short somewhere since I had 4x PCB made and all of those have the same issue.

elessargr , 08-31-2025, 09:50 AM

Robert This is what I was thinking also! Getting that hot soo quickly I dont think is normal.
I have some basic tools which I believe can do what I need.
I will check each input for the IC.
Thanks!

elessargr , 08-31-2025, 06:53 PM

okay so managed to check the voltage on power pins.
I marked them with orange the values that my multimeter gave me. 🙂
The only ones that looks weird to me are the pin5,8 since on the one side of the resistor we have 3.33v and on the other 3.3v.

For the current still checking how to do this on a PCB

Robert Feranec , 09-01-2025, 02:46 AM

if there would be problem you would probably see a high drop on the voltage rails, but depends on how strong your power supplies are. did you try to check the whole board power consumption? It still could be the thermal connection (not enough vias on the copper under the exposed pad), but if the hub is only connected to power and nothing else is connected I would expect the chip to stay cold or maybe only a little bit worm .. I would not expect it to get hot within 1s. BTW, does the board work?