DP83TC812S-Q1: Ground shift between connected Ethernet Phys

David Shumate

Part Number: DP83TC812S-Q1

Hi Team,

My customer is looking to connect 2 ECUs via ethernet and they have a spec that shows the two ECUs could have a ground shift differential of up to 2V when comparing one to the other.

With this, can you clarify if either of the two situations are of any concern:

1. There is a DC 2V difference between grounds of two connected Phys

2. During operation there is a transient 2V ground differential (only for a few us/ms) between the two Phys.

If this is covered by an ISO ethernet specification, any information about that would be helpful.

Best,

David

over 4 years ago

0 Joe Vanacore over 4 years ago

TI__Genius 17530 points

Hi David,

The decoupling caps should take care of the DC difference in your first question.

Can you refer to the test specification that you are referring to for the transient 2V differential?

Our ethernet PHYs are compliant to EMC as defined by Open Alliance.

Kind Regards,

Joe

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (www.ti.com/.../important-notice.shtml)

0 David Shumate over 4 years ago in reply to Joe Vanacore

TI__Expert 8355 points

Joe,

I appreciate the feedback. This was purposed more as a hypothetical form the customer for instance if a motor was driven by the ECU caused one ground to bounce in respect to another ECU. With that I don't have a specific test specification.

Best,

David

0 Joe Vanacore over 4 years ago in reply to David Shumate

TI__Genius 17530 points

Hi David,

I will reach out to the design team for more information. I hope to get you a response by the end of business Monday.

Kind Regards,

Joe

0 Joe Vanacore over 4 years ago in reply to Joe Vanacore

TI__Genius 17530 points

Hi David,

This is not a usual test and it can definitely affect the PHY's performance.

We don't do any testing related to this and we suggest that the customer resolves this transient behavior on their system level.

Kind Regards,

Joe

Interface

Interface forum

DP83TC812S-Q1: Ground shift between connected Ethernet Phys