• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 30 subscribers
  • Views 591 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TM4C1294NCPDT: Radiated emission test fails when communicating on Ethernet

Prassanna Sakore
Prodigy 170 points
Part Number: TM4C1294NCPDT

Hello,

We are using our product to send data from Ethernet to Serial.

The device fails RE test due to some reason. We have followed every step given in system design guidelines.

The only part which seems to emit is Ethernet. What could be done to solve the Emission problem? please suggest.

We use cat6 cable for Ethernet.

The following image shows the layout.

Can the Rx and Tx line be swapped for reducing the length of tracks as it supports auto-mdix?

  • 0
    TI__Guru 72500 points

    I may be having trouble interpreting the schematic from your layout, but that does not look like the recommended circuit from the datasheet or the recommended layout from the design guideline.

  • 0 in reply to Bob Crosby
    Prodigy 170 points

    Hello,

    This is the schematic of the above layout. We are using a connector with inbuilt magnetics therefore the layout doesnt look the same. But the differential line are routed parallel in the layout with keeping the track parameters as suggested in the guidelines.

    Please suggest what could be done.

  • 0 in reply to Prassanna Sakore
    TI__Guru 72500 points
    Changing the parts list and the layout does affect the radiated emissions. Meeting your radiated emissions test limits with your design is beyond the scope of what I can do for you on this forum. If you don't have the necessary EMI experts in-house, you may want to consider hiring an expert consultant.

    Switching the TX and RX pairs is purely an application decision and should not be a problem if always connecting to an Auto MDIX switch. While that can shorten the routing under the RJ45 connector, I don't know if that will solve your emission problem. Moving the RJ45 connector on the other side of the board would have a similar impact.