nRF52840 QFAA sensitiv to magnetic flux (custom board)

RE: nRF52840 QFAA sensitiv to magnetic flux (custom board)

uknoblic — Fri, 14 Mar 2025 08:48:47 GMT

Hi, the root cause is very simple - once you use an unshielded inductor for the DCDC converter, this will simply saturate in presence of a magnetic field. Take a shielded one, then this problem disappears ;-) Solved...

RE: nRF52840 QFAA sensitiv to magnetic flux (custom board)

uknoblic — Tue, 03 Dec 2024 12:16:08 GMT

By the way, meanwhile i figured out that the root cause for the increase current consumption seems to be the DCDC converter. When i turn it off via

  NRF_POWER->DCDCEN = 0;

i can't see any influence when i bring a magnet close to the PCB. The assumption is, that the chip inductors will saturate in this situation. I will double check this with a DK and come back to you

RE: nRF52840 QFAA sensitiv to magnetic flux (custom board)

uknoblic — Fri, 04 Oct 2024 08:04:28 GMT

Good morning Kenneth, it'll need some days until the DK will arrive. I will come back to you.

RE: nRF52840 QFAA sensitiv to magnetic flux (custom board)

Kenneth — Wed, 02 Oct 2024 10:59:33 GMT

Hello,

This is a first yes, do you see the same on the DK? I am thinking it's something else than the nRF52840 IC yes, possible the "can" of the 32MHz or 32kHz crystal that somehow magnetize and create a short of some kind. ~10mA is also a very strange current, the only thing close to this would be the radio actively transmitting or receiving, though I guess if you somehow stop the 32MHz it will also stop code execution. But it's slighty far fetched. If you can provide details on how to recreate this on a DK I am sure I will try to look into it more.

Kenneth