RAK1920 - 3V3_S issue


I have a simple issue : I have a combinaison of RAK 4631 + RAK 5005-0 + RAK 1920 (no part have been modified at all, all is brand new) and I still don’t know why, but the 3V3_S and VDD seems linked.

As I was trying to connect a QWIIC sensor, I saw that it was powered even when IO2 is low, I disconnected it and with my ohmmeter I tested every link. I found that VDD and 3V3_S are linked when RAK 1920 is plugged.

Any idea ?


Welcome back @Batto

I checked the schematics and there is a bug on the RAK1920. 3V3 and 3V3_S are connected to each other, which should not be. Unfortunately it cannot be changed (no 0 Ohm resistors there).


I reported to R&D, but on the current PCB’s it is like this.

Sorry for that.

Uuhh in the official doc, it’s not this schematic :


It might be updated, but there might be versions out that have the connection.

But they have a different version number ? Mine is “Ver. A”
Is there any chance I can cut a trace to correct the problem on this version ?

The changed boards (I checked, it was corrected 10 months ago) will have Ver B. But I am afraid there was a lot of stock and they were still sold.

It is not possible to cut a trace, the wrong connection between 3V3 and 3V3_S is below the IO connector.

Yes even if I’m used with SMD it’s a little bit tricky ^^’

I bought it months ago so it’s not so crazy to think I was an early adopter.

Anyway I was interested in QWIIC connectoc and the new dedicated WisBlock is more interesting so …


If you need a QWIIC connector, this might be a better solution: QWIIC Module RAK13009.
On that one we didn’t make the mistake with 3V3 and 3V3_S

Yes I was talking about it :wink:

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