DEC5 pin capacitor of the nRF52840

[XWH]

Hallo，

    What’s the purpose of connecting an 820pF capacitor to the DEC5 pin on the nRF52840 hardware versions before Fxx? For the chips shipped later, will the version be the latest Fxx, or will Dx versions also have it? Why?

Thanks！

[SwRa]

Hello,

On the nRF52840 for build codes Dxx and earlier, the DEC5 pin functions as a power pin for 1.3 V regulator supply decoupling. The 820 pF capacitor (designated as C9 in the reference designs) provides internal decoupling for this regulator. For build codes Fxx and later, internal chip revisions made the external decoupling capacitor on DEC5 unnecessary, and the DEC5 pin is designated as Not connected (N.C.) 

Newly manufactured chips from modern production runs will be version Fxx or later. Unless you receive older distributor/inventory stock that was produced before the F revision, new parts should be Fxx or newer. You can check the package marking/build code to confirm this.

Best Regards,

Swathy

[XWH]

Thank you for your reply, but I have another question: was this chip manufactured in the 20th week of 2025, or is there a reason why there is a Dxx version of the chip?Silkscreen reads N52840CKAAD12520AC。

Thank you！

[PaKa]

The one in the picture looks like they are build code D20 built in week 17 of 2026.

The text version looks like a D revision silicon from week 20 of 2025.

There are separate ordering codes for the nRF5240,

The ones without the -F (and that are marked "Not recommended for new design") will all be revision D, all the ones with the -F will be revision F.

Which revision you will receive will be determined by which ordering code you use, we recommend to migrate to the -F version.