understanding the accuracy/precision of LFRC on nRF52833

RE: understanding the accuracy/precision of LFRC on nRF52833

Kazi Afroza Sultana — Tue, 19 Nov 2024 13:24:20 GMT

Hello,

For LFRC, Frequency tolerance after calibration is +/- 500ppm. With proper calibration it is achievable. I will talk to relevant team to know about the effect of temperature drift on accuracy.

RE: understanding the accuracy/precision of LFRC on nRF52833

mmdunc — Fri, 15 Nov 2024 16:26:01 GMT

Thanks for forwarding this, in the post it's asserted that "The frequency drift of the RC is in fact a result of temperature change" and that "The chip have an internal RC oscillator that has an accuracy of 250 ppm when calibrated".

Interestingly It looks like the nRF52833's RC is 500ppm when calibrated, instead of 250ppm for the nRF51.

How is this accuracy spec defined? I assume 500 ppm is with respect to the calibrating clock (HFCLK), not absolute accuracy? As far as I can tell there's no accounting for the thermal drift of the HFCLK in this process, so the true accuracy may be lower (or perhaps the 500ppm encompasses thermal inaccuracy of the HFCLK?)

RE: understanding the accuracy/precision of LFRC on nRF52833

Kazi Afroza Sultana — Wed, 13 Nov 2024 14:55:37 GMT

Hello,

There is an old case (+) What low-frequency clock sources can I use? - Nordic Q&A - Nordic DevZone - Nordic DevZone you can look at. I believe you will find a lot of relevant things here.