Apalis iMX8 carrier RGMII interface Layout guideline and HDMI ESD protection chip solution

Hi Support Team,

We are working on Apalis iMX8QM customized carrier board design and kindly please advise on below related issues:

  1. we will have a Microchip ethernet switch chip on carrier connected via Apalis iMX8 RGMII interface, any related layout guideline for this interface? on Apalis iMX8 module, is length maching route placed from iMX8 pin to MXM edge connector for both Rx and Tx related signal groups?
  2. for HDMI interface, per Ixora latest V1.2 carrier reference design, there is a Nexperia IP4786CZ32 ESD/DDC buffer chip adopted, but on Nexperia website, this part is claimed as not recommended for new design, so any replacement suggested for this part?

Thanks and Best Regards


Hi @hai.tx

  1. Yes, the RGMII signals are length matched on the module. The signals are matched over all the signals, not only within the RX and TX group. This means the customer has to match them only on the carrier board and does not need to take into account any length differences in the module. The signals are routed with impedance controlled 50R traces. I recommend to route them also with 50R impedance on the carrier board.
  2. We are currently evaluating a replacement for the Nexperia device. Currently, the preferred candidate is the HDMI2C1-14HD, since it is HDMI 2.0 compatible. However, the decision has not been taken.

Hi @peter.tx ,

appreciate your detailed reply, it really helps us a lot!

Hi, I got questions from customers about how the evaluation of the HDMI2C1-14HD went.
I guess we can say that we will go with this chip.

Best Regards,

Matthias Gohlke

Correct, we are using the HDMI2C1-14HD on the new version of the Dahlia carrier board.