https://devzone.nordicsemi.com/f/nordic-q-a/58238/the-question-of-tolerance-of-crystal-hfxoHi Sir, According to the datasheet of 52840 (v1.1), in the ref. schematic, the requirement of 32M is +/- 40 ppm. In section 5.4.4.2, for the frequency tolerance requirement of the long packet, it is +/- 30 ppm. If we use +/` 40 ppm 32M crystalen-USTelligent Community 13Mon, 24 Feb 2020 14:38:07 GMThttps://devzone.nordicsemi.com/thread/236015?ContentTypeID=1Mon, 24 Feb 2020 14:38:07 GMT137ad170-7792-4731-bb38-c0d22fbe4515:aacd180d-f2b7-4245-bb79-513a5b7d3cefhaakonsh<p>If you do not use a +/- 30ppm crystal then you&nbsp;will experience packet loss, and you will not most likely not pass BT RF-PHY certs for Coded-PHY.&nbsp;<br /><br />You should use the most accurate crystal that fits your needs. Note that the +/- 30ppm limit includes crystal tolerance, temperature drift, and crystal aging. You need to add the effects of temperature and crystal aging over the lifetime of your device.&nbsp;</p> <p>For instance, a typical&nbsp;32MHz crystal for consumer use can have a Frequency Tolerance of +/-20ppm, a Frequency shift by temperature of +/-20ppm, and aging of +/-5ppm per year.&nbsp;<br /><br />The worst-case scenario after 3 years of operation at high or low temperature is then&nbsp; +/-(20ppm + 20ppm + 3 x 5ppm) = +/-55ppm.&nbsp;</p><div style="clear:both;"></div>