IMX7D and PF3000 : PWRON signal

[Madwo]

Hi support,

I have a question about the behaviour of the PMIC PF3000 and the IMX7.

I work with a PICO-IMX7 from TechNexion. I can plug this SoM either into a kit (PICO-PI) or onto a custom board I've made myself.
My problem is that it doesn't boot when I plug it into my custom board, but it boots just fine on the kit. By connecting an oscilloscope, I can see that it tries to boot continuously but it doesn't succeed.

In this document: https://www.nxp.com/docs/en/data-sheet/PF3000.pdf, you can find this image showing the different start-up timings

So I measured these signals on my PICO-IMX7 to be able to compare. Below you will find two oscillograms: the first is the behaviour when I plug the PICO-IMX7 into the kit and the second when I plug the PICO-IMX7 into my custom board.
VIN = yellow
VSNVS = purple
PWRON = blue
RESETBMCU = green

The sequence on the kit is identical to what is shown in the datasheet.
However, for the second oscillogram, the blue signal (PWRON) does not remain in the high state. We only see a pulse and not an edge.
The PWRON pin is an input for the PMIC and so it's the IMX7 that has to set this pin high but it doesn't manage to do so.

I've looked for documentation on how this pin works for the IMX7, but I haven't found much, which is why I'm writing to you here.

Do you know why the IMX7 cannot keep the PWRON pin high?

Thank you in advance

Best regards.

[riteshmpatel]

Hi @Madwo,

I hope you are doing well.

Is the PMIC_PWRON signal controlled from the Base Board? Could you share more details on how it is being connected?

Thanks & Regards,
Ritesh M Patel 

[Madwo · Accepted solution]

Hi,

Thank you for your support. I finally found the reason of my problem. On the baseboard I have a watchdog connected to the PWRON signal too. It was the reason why the signal went to 0.

Have a nice day.

Best regards.

[riteshmpatel]

Hi @Madwo,

Good to hear that the issue is resolved. Thanks for the update.

Thanks & Regards,
Ritesh M Patel