Is NRF52840-QIAA-F a drop-in replacement for NRF52840-QIAA?

[Steve Van Kirk]

Near as I can tell from v1.7 of the product specification, these two parts have the same footprint & pin-out because they're both aQFN packages (as indicated by the "QI").  

What isn't clear from the spec is this:

1. What are the differences between them?
2. Why is the QIAA not recommended for new designs but the QIAA-F seems to be OK?

Ultimately I'm trying to figure out if I can use the QIAA-F as a drop-in replacement for the QIAA.

infocenter.nordicsemi.com/.../nRF52840_PS_v1.7.pdf

Thanks!

Steve

[aoliveri]

Hi Steve,

The Access Port Protection “APPROTECT” mechanism has been improved, and we published a blog for working with the new revision:  https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/working-with-the-nrf52-series-improved-approtect

Note the link within the blog to Info Notice 141 https://infocenter.nordicsemi.com/pdf/in_141_v1.1.pdf?cp=18_16 which should answer all of your questions. 

[Steve Van Kirk]

Thank you - this was very helpful.  Nordic reached out to me separately and also clarified that the DEC5 pin (N24) was disconnected between the package & the die on the -F version.  So if you already had a capacitor connected to that pin for the QIAA version, leaving the capacitor in place wouldn't cause any problems with the QIAA-F.  It would just be an extra part on the board.

One could perhaps have assumed this from the information available, but it was nice to have it confirmed.

Thanks again!

Steve