https://devzone.nordicsemi.com/f/nordic-q-a/62590/nrf52840-external-32-768khz-crystallHi everyone, I am desing my own pcb using nRF52840 SOC. Looking the reference design I can see two external crystalls one 32.768kHz and one 32MHz. 1. The 32.768kHz is used by the RTC isn&#39;t? So without this crystal I cannot use the RTC and thereforeen-USTelligent Community 13Mon, 15 Jun 2020 12:10:24 GMThttps://devzone.nordicsemi.com/thread/255000?ContentTypeID=1Mon, 15 Jun 2020 12:10:24 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c0b3b502-924a-468c-a9d4-cb4cf882c4beNikosant03<p>Understood, thank for your support!!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/254988?ContentTypeID=1Mon, 15 Jun 2020 11:41:57 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d0479f52-263a-493a-8f7a-4ceb69f493cahaakonsh<p>The crystal has lower current consumption and it is more accurate and stable over temperature.&nbsp;</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/254984?ContentTypeID=1Mon, 15 Jun 2020 11:38:26 GMT137ad170-7792-4731-bb38-c0d22fbe4515:42178491-fcae-449f-a05f-17fcb71415e1Nikosant03<p>Thanks for your reply,</p> <p>What is the purpose of the external&nbsp;<span>32.768kHz clock if I can use the internal one? If it is something that is not critical I am considering of ommiting from my design.</span></p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/254977?ContentTypeID=1Mon, 15 Jun 2020 11:11:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6fbaecf3-64a7-484a-b691-03774344ad69haakonsh[quote user=""] If this is true why is it mentioned as <strong>optional</strong> on the reference circuit[/quote] <p>&nbsp;It&#39;s not true, there&#39;s an internal 32.768kHz RC oscillator that you can use.&nbsp;</p> [quote user=""]What is the purpose of&nbsp;32Mhz crystal? Is it vital?[/quote] <p>It is required if you intend to use the RADIO peripheral. The 2.4GHz radio requires a very accurate clock source for its PLL.&nbsp;</p><div style="clear:both;"></div>