Latest (1.1) nRF52832 QFAx reference design confusion

[Lauri Jämsä]

Hi,

I noticed you have added C13 and C14 (12pF) caps. However, they are not visible on Infocenter's reference circuitry. What are these caps for and why they should be used?

Another question:

Earlier you removed DEC2 cap (C6) from reference design. After this, we haven't populated it either. Is this documented somewhere and why it's not needed any more?

[Hung Bui]

Hi Lauri,

We updated the reference design due to a PAN (ERRATA) we found lately. Please refer to the Errata here. It's at PAN #138.

Please note that, you only need these 2 caps if you plan to use P0.25 and P0.26. If you don't use them you can simply connect them to the center pad to save cost and space.

Regarding your second question, C6 only needed for WLCSP and not needed for QFN48 package, so you don't need to populate it in your QFN design.

[Sam]

My design is already in production for US and we just started to cert CE. The device failed currently, and passed only when we tied these two pins to GND. Before booking another trip to the lab, will it be the same by driving '0' on P0.25 and P0.26 in high drive mode? Will this pass CE limits? Thanks.

[Hung Bui]

Hi Sam,

It should be fine, just set P0.25 P0.26 and P0.27 as output as set them to 0.