B523 custom hardware not working

Hi. I have made a custom pcb for the B523 SoM. When I boot the system the led flashes green like normal to connect to cell. After a few seconds he led stops blinking green for a short second and then flashed white one time, and then back to blinking green again for some time. This cycle continues indefinitly. I have no other components on the card for testing purpose. I feed 3.8v and 3.3v to the module. What could cause the crash? Not sure how to debug this. Any help would be greatly appreciated. :

One cause of that behavior is there is not enough current and when the cellular modem is trying to connect it’s drawing too much current and causing the nRF52 to brown out and reset. That’s the white blink.

What does your power supply look like, and what is powering it?


Thank you so much! Well it turns out that I used a XCL223A333D2-G for the 3.3v rail, but that was not enough. Replaced it with a larger one for test and it worked fine. :slight_smile: