What is the safe Maximum volage for the C10 (DEC4 Cap) on PCA10040 (nRF52 DK)

[BSharp]

Hey I'm looking at the radio page for the nRF52 DK and at there is a Capacitor C10 that goes between the DEC4 and VSS pin.

The BOM for PCA10040 shows the following line:

C10, C16, C17 1.0µF Capacitor, X7R, ±10% 0603

I also looked in the infocenter page and it is listed as C9 there

infocenter.nordicsemi.com/.../ref_circuitry.html

It also has slightly different specs on the info page BOM part:

C9 1.0 µF Capacitor, X5R, ±5% 0402

So I get it needs to be 1.0uF and I'd assume the later version of the PCA10040 packages are more accurate and so I'll get a X7R but what should be the maximum voltage for this capacitor?

Thanks!

[MartinBL]

Hi,

Sorry for the late response. I got some input from the designers:

1. The maximum voltage on DEC4 is 1.32V. With 50% derating, we are still at a very low level. Generally voltage tolerances won't be a problem here as capacitors are typically 4.0V, 6.3V,10V,16V etc. in 1uF 0402 or 0603 packages.
2. The capacitor type has to be general X5R or X7R. The difference between the two is just temperature dependencies. Other types of capacitors, especially not temperature compensated ones, are not allowed.

I couldn't get a proper answer to why the BOM of the DK kits may differ from the reference circuitry. It may have been design choices made at the time based on other things than the value, such as package type, cost, availability, etc.