iMX7 power-up sequence

Hello.
This question is related to this ticket. We are facing the problem that the ethernet connection stucks sporadically. Some of our modules are showing that issue, some not. All are working on the Viola carrier board. Now i investigated the power-up sequence. Please have a look at my measurements of the 3.3V power rail during power-up: [upload|ynDMgU4mvcS7nbqfTuBLv8hRBnY=]

We are generating a lot of voltages out of the main power supply and each rail draws some ampere. Question is, is this behavior okay as the reset line is released much later (orange line)? The Colibiri datasheet states that “It is important that the main input voltage rises monotonically”, but however, the main power supply is stable when the reset line turns inactive. For reference this is the power-up measured on Viola: [upload|QPrxyAkmHEtXPHiDgsNEb6IM/T4=]

Thanks in advance.

Hi @qojote

Thanks for writing to the Toradex Community!

Please have a look at my measurements of the 3.3V power rail during power-up:
The Colibiri datasheet states that “It is important that the main input voltage rises monotonically”, but however, the main power supply is stable

I don’t see in the upper graph, when the reset line becomes inactive. Could you try to show this?

Best regards,
Jaski

Please see the attached image for the reset line timing.

Hi @qojote

Thanks for sharing this image of reset line timing.

So are you keeping the reset line down on your carrier board, since if you use viola board, then the reset line goes up very fast ( after some ms)?
Nevertheless, we don’t think that the ramping up of the VDD should create an Issue on the PHY. However you can try to switch the power-rail of the PHY off after boot-up of OS and on again and check if you still some issues on the Ethernet.

Best regards,
Jaski

Problem is solved. The power-up sequence was not the reason for our ethernet problems.

Perfect that it works. Thanks for the feedback.