DP83867IR: voltage differences for TDSET3 Ethernet Compliance Test

just to add for your understanding.

The test was performed under the guidelines of "How to Configure DP838xx for Ethernet Compliance Testing" - our app note.

It was measured with a DPO7245 with differential probe P6248.

the deviation is measured with the peak voltage test (2.2.2).

Thank you for you efforts,

Marion

Hi Marion,

Are they following the same register configurations that are in the app note?

We test PMA using the same software and also run at a 3rd party test house called UNH IOL.

Please send me the schematic of the customer board for the 867 as well as part number for the magnetic they are using.

Hi Ross,

I got the required input but I don't feel comfortable posting them.

I'll  provide them in a separate private mail and you can comment then.

Kind regards,

Marion

Hi Marion,

Thank you for the data and the schematic.

I looked at the magnetics but could not find any details on their winding accuracy.

Could you check with the customer to see what those specs are?

Please have them re-run with the ESD removed. I would like to see how much those external devices are influencing the symmetry.

When they do the testing, what length cable are they using for the TDSET3? Is it the short standard cable that comes with the software suite?

Hi Ross,

do you mean by removing ESD?

Kind regards,

Marion

Hi Ross,

I have some answers from the customer:

1) ESD Protection and Cable Information: 
 
I wrote a protocol about the measurements I made referring to this problem. I tested two different cables and unsoldered the TVS Diode. There was no improvement trough this steps. The results of chapter 2.2 and with the black cable are measured with the short cable included in the compliance test hardware.

2) Connector/Transformer:

We are using connectors with integrated transformers marked as suitable for 1000 Base-T. Are there any special requirements by the Phy? I will request that parameters by the manufacturers if you could give me some more information about that. (As I can not find any more detailed information inside the datasheets either for the winding accuracy). 

I'm still awaiting, what you meant by removing ESD.

Please provide an answer as soon as possible.

Kind regards,

Marion

Hi Marion,

For the ESD (TVS), we have seen that if the loading of the TVS is high >10pF, you can see degradation in return loss and face balancing issues.

This is why I had asked to see the measurements with and without the TVS. 

Please re-run the test multiple times to see if there is any run to run variability.

Pair A, B, C, and D showing much difference with run-to-run?

I did provide the report to you directly.

Please follow up as soon as possible for you.

Kind regards,

Marion