Can we trim the 32MHz XTAL frequency in production?

[lykkeberg]

We are developing a Bluetooth device around the nRF52840 SoC. The time has come to investigate the production part of things.

Since we have been developing and designing with Dialog Semiconductor, Texas Instruments and Silicon Labs Bluetooth Low Energy SoC's previously, we are a bit confused to why we cant seem to find any documentation or description of how to trim the 32MHz XTAL frequency in production.

All the SoC's just mentioned, has a special trimming capability, which makes it possible to "remove" the initial frequency deviation from the XTAL in production. This is typically done by programming some "digital capacitor" in the SoC.

Our question is then: Do Nordic Semiconductor nRF52 series (or any other for that matter) have this capability or do we simply need to design with the low-tolerance crystals?

Kind regards

Thomas Lykkeberg

[ketiljo]

Trimming in production is not an option for any nRF52 device. You typically select a crystal with sufficient tolerance (total better than 40 ppm) and use the appropriate load capacitors. 

The nRF53 series have built-in and selectable capasitors to do without external load caps.