TM4C1294KCPDT: : Ethernet signal layout query

Tusarkanta Das

Part Number: TM4C1294KCPDT

Hi,

In our application, we are using M12 (4-pin ) connector for Ethernet connectivity. As per standard pin configuration of M12 connector, all signals routing in top layer is not possible, so 1 signal routed in 2 different layer through VIA. As per guidelines all signals routing should be in top layer without any VIA .

As the layout revision is going on, please advise best possible way to route Ethernet signal.

Existing routing details:
- TX_N, RX_P & RX_N : Routed in top layer
- TX_P : Routed in top & inner layer
- differential spacing not tuned to the PCB stack-up for 100Ω differential impedance.
- Only differential routing & length matching done.

Please refer attached layout image for reference & suggest the solution to improve layout ASAP.

Thanks,
Tusarkanta Das

over 5 years ago

0 Ralph Jacobi over 5 years ago

TI__Guru*** 135355 points

Hello Tusarkanta,

There are ways to do the routing properly and you can see that with this TI design: http://www.ti.com/tool/TIDM-TM4C129USBHS

The PDF for the PCB layers shows this on Page 1: http://www.ti.com/lit/df/tidrpl6/tidrpl6.pdf?ts=1590524453856

The 100 ohm differential impedance is very critical for proper operation and must be addressed as part of this layout.

That TI design and our System Design Guidelines are the best recommendation we can make. We do not have detailed hardware experience for Ethernet layout to handle abnormal routings or offer guidance for that. It's beyond what we can support as device experts.

If you believe that is not sufficient background to work with from a layout perspective, then you may want to consider getting help from a third party regarding this, I know one of our third party partners does consulting and has a lot of Ethernet experience: https://www.elco-solutions.de/

0 Tusarkanta Das over 5 years ago in reply to Ralph Jacobi

Prodigy 80 points

Hi Jacobi,

Thanks for the reply.

We will try to modify the PCB as per guidelines shared .

If any help required, I will contact you.

Regards,

Tusarkanta Das

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TM4C1294KCPDT: : Ethernet signal layout query