52832 P0.25 and P0.26 problem

[William.wei]

hi support team,

customer 52832 product had problem that they can't pass fcc test,the reason for this is they forgot to add capacity to those pins.

their design is:

and our refrence design is:

also we had errata to clarify about this.

now my question is , Is there any way to solve this by software instead of adding capacity, cause it is pre-production period, not easy to change the hardware right now.

Regards,

William.

[helsing]

Hi William,

I am looking into this. It might be possible to configure the IOs in a way that is more favorable for the radio. I will get back to you when I have more information.

Regards,

Håkon

[helsing]

also we had errata to clarify about this.

Is this the nRF52832 Revision 3 Errata Item 138?

Another case mentions that grounding the pins would help. Edit: I suppose one could ground them internally. Grounding will have to be done externally. There is no software fix for Item 138.

they can't pass fcc test,the reason for this is they forgot to add capacity to those pins.

Do you have any more information regarding how the device fails?

Would it be possible to see more of the schematics? We could make the case private if necessary. It would be interesting to see what else is connected to these two pins when considering an alternative solution.

Regarding a future hardware fix or patch: 12pF capacitors are recommended. However, the value of the missing capacitors is less important critical than and the same value as the crystal loads can be used. The important thing is that they are placed very close to the pins and that capacitors have high quality grounding. 

[helsing]

It would be key to know more about how the customer's device is failing FCC. Errata Item 138 is related to ETSI requirements so this could be something else.

The fix with the capacitors only helps for RX mode.

[William.wei]

Yes Helsing,

it is related to errate 138----adding capacity to this, now adding capacity to 25 and 26 pins can solve this problem. i have confirmed with customer.

so according to you ---"There is no software fix for Item 138." Just want to confirm this from you.

and bluetooth hardware design should not much change according to our reference, except 0.25 and 0.26---customer told me about this .

and testing is about "secondary harmonic" item, not details because we solved this issue quickly

Regards,

William.

[Kaja]

Hi, 

there is no software option to errata 138.. so the recommendation is capacitors, or if the pin's are not in use, they can ground the pin's instead. 

Best regards,
Kaja