Pins marked as n.c. in datasheet nRF5340-QKAA. What to do with them on the PCB?

[henning larsen]

The datasheet list 

A25, B12, B26, D2, F2, G1, H2, J31, K2, T2, AG31, as N.C.

I have not been able to read exactly what N.C. implies: It could be: "do not connect", "no internal connection".

If one for clarification looks at the example circuits in the dataheet some of these pin, but not all are connected to Vss (gnd)

The connected pins are:

A25, B12, B26,              G1, H2, J31 

So it means that D2, F2, K2, T2, AG31 are left unconnected. A bit unclear which rule to follow.

Bottom line of my question: what is the required connection for pins marked N.C.

Thanks

[Priyanka]

Hi,

The N.C means Not Connected. These pins are dummy pins for mechanical stability and not internally connected to the die of the SoC. Some of them are connected to VSS because of the layout and this helps in grounding and also, as I mentioned earlier, the mechanical stability. So you don't need to connect them. It's okay to leave them "not connected".

Best Regards,

Priyanka

[henning larsen]

thanks for swift reply. Can I ask you to verify if I am correct that this information is not written in the datasheet.

If so, please add it to the updates list - It is not good to have ambiguous information in a datasheet

br henning

[Priyanka]

Hi Henning,

It's mentioned under the QSPI pin assignments section:

-Priyanka

[henning larsen]

Hi Priyanka,

Sorry but this is incorrect - I am looking at nRF5340 chip and not nRF52. And if you open the associated tab similar to the one you link to for nRF52xx then there is no info. Samme goes for the pdf datasheet nRF5340 Product Specification v1.3.

ps. It is slightly annoying that you cant link to specific pages. I tried to copy paste an image but this does not work either.

henning

[Priyanka]

henning larsen said:

. And if you open the associated tab similar to the one you link to for nRF52xx then there is no info.

Sorry, I got confused with another case of mine. Yes, it seems like it's not mentioned. Thank you for alerting this. I will report it internally.

henning larsen said:

It is slightly annoying that you cant link to specific pages.

Yes that's true, we have this problem with the Infocenter.

-Priyanka

[henning larsen]

great - and I see that you _can_ copy paste an image to the dialog without having to do all the tedious pass via file upload - sooo practical.

[henning larsen]

but please when updating you documentation: Think in the terms of the user and do not just mark not connected. The user need to know what that implies with respect to the use of the part.

I.e. It can mean:

1. Do not connect any copper but the solder pad to this pin
2. No internal connection - You can connect to this pad if you need to pass through with a trace

So N.C. need to be specified. For nRF5340 I deduce that it is option 2 which applies.

And now I will stop.

[Priyanka]

henning larsen said:

For nRF5340 I deduce that it is option 2 which applies

Yes, that's right.

henning larsen said:

but please when updating you documentation: Think in the terms of the user and do not just mark not connected. The user need to know what that implies with respect to the use of the part.

I think that's a great suggestion Thank you very much.

-Priyanka