Jetson Nano on the custom Carrier board Power-On problem

Hello, I have a project creating a Carrier board for a Jetson nano, trying to expand every possible peripheral. Refer to the datasheet and device instructions.

[ Circuit design ]
The circuit design and selection of part numbers for all components I refer to the OrCAD schematics from Jetson download center. However, some components were not widely available at the time. So I replaced it with another part with similar specifications. such as (OrCAD’s part → Replaced), (DMN26D0UFB4 → FDY301NZ), (2N7002DW → NTJD5121NT1G) and replaced the power switch of HDMI and DP by BD2222G-GTR. And check the component that has NO STUFF specified. I understand that there is no need to place that component when assembling. Specifically, a 0 ohm resistor.

[ Plug the power ]
I’ve tried powering it with 5V 2A DC Jack Adapter, but the circuit to switch power between the DC Jack and Micro-USB is incomplete. But the board is still powered normally and the SDK Manager can find the Jetson nano connected via Micro-USB in Recovery mode.

I was install the Jetson nano SOM on a SODIMM and tried powering the Carrier board, and then I found that the LED that was triggered by the PWR_LED_CTRL pin came on. And I measured the voltage on each net, for example VDD_5V_IN, 3.3V from Buck converter, 1.8V from LDO regulator and the voltage on the port of HDMI and DP. which all came out normal.

Then I connected my screen to the Carrier board with HDMI hoping it would show up. But nothing happened. So I’m not sure if the Jetson nano has turned on correctly.

[ Debugging ]
I measured the POWER_EN and SYS_RST signals coming out of the SOM to check if they followed the Design Guidelines, and they did.

And I have connected the UART2 to the Docklight on the net after the voltage translator and directly on the SOM pin, and no message appears on both.

Moreover, I don’t know what issue I should investigate further.
Thank you

Why is there a drop on POWER_EN when 5V is ON?

It is hard to tell what the issue is. You should refer to P3449_B01_Concept_schematics.pdf not OrCAD file as there might be some bom difference between. And there is schematic checklist sheet attached in Design Guide doc, you can check your design based on that first.

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