TUSB1046A-DCI: Low temperature failures

Hi,

How is the cold temperature being applied? 

Are you able to take a USB trace to see where we are seeing the issue?

Can you capture an eye diagram at the output when cold starting under 0C and when ramping under 0C to see if there is a difference in signal quality?

Are all parts in the signal path rated for under 0C?

Hello Vishesh,

The chassis is inside an temperature chamber

I am not sure what USB trace means? Please elaborate

It is difficult as the chassis is enclosed where the PCBs are within

Yes, all parts are rated -40 to +85 C

What happens at lower temperatures and does the equalization value change? Do the PCB traces have an effect at lower temperatures as well? It works fine if the unit starts at room temperature and is cooled down even up to -32 deg C. It is only when it is cold started at lower temperatures where the USBs do not work.

Thanks,

Divakar

Hi,

Ramgopal Divakar said:

I am not sure what USB trace means? Please elaborate

This is a USB protocol trace. This will allow us to see what packets are being sent and what may be causing the hang up in USB connuncation.

Ramgopal Divakar said:

What happens at lower temperatures and does the equalization value change? Do the PCB traces have an effect at lower temperatures as well? It works fine if the unit starts at room temperature and is cooled down even up to -32 deg C. It is only when it is cold started at lower temperatures where the USBs do not work.

This is unexpected behavior as we can see the performance does not drop when the part starts up at room temp and is cooled down.

Are you able to test this and recreate the issue on the TUSB1046 EVM? Can you reproduce this issue across multiple boards/ parts?

There will be some differences equalization with changes in temperature. However, this may not be the root cause especially if the part works when its cooled down as the link is on. Would any startup timing change with the cold temp?

I will reach out to our systems engineer for more info.

Hi,

Ramgopal Divakar said:

I am not sure what USB trace means? Please elaborate

This is a USB protocol trace. This will allow us to see what packets are being sent and what may be causing the hang up in USB connuncation.

Ramgopal Divakar said:

What happens at lower temperatures and does the equalization value change? Do the PCB traces have an effect at lower temperatures as well? It works fine if the unit starts at room temperature and is cooled down even up to -32 deg C. It is only when it is cold started at lower temperatures where the USBs do not work.

This is unexpected behavior as we can see the performance does not drop when the part starts up at room temp and is cooled down.

Are you able to test this and recreate the issue on the TUSB1046 EVM? Can you reproduce this issue across multiple boards/ parts?

There will be some differences equalization with changes in temperature. However, this may not be the root cause especially if the part works when its cooled down as the link is on. Would any startup timing change with the cold temp?

I will reach out to our systems engineer for more info.

Can you confirm that I2C is functional at the low temp?
Normally EQ increases slightly at lower temperature

I2C from the Infineon (Cypress IC?) to the TI IC. I assume it is as the monitor works even though the USB doesn't. They go to the same Anker adaptor. 

I do not have the evaluation board. At this point I don't know where the fault lies. It definitely seems to be a power up situation.

Thanks for getting us help from your System's Engineer.

Yes, It seems to be a startup issue. 

What are you able to probe/ test?

I will send you the USB-C captures. I have a tool from Infineon/Cypress. Let us take it from there.

sounds good!

let me know when you will have data available.

I have requested friendship. Let me know. I can't attach my schematics etc here. It is sensitive data.

Got it, yes I accepted your friendship request.