https://devzone.nordicsemi.com/f/nordic-q-a/46396/why-does-the-nrf52840-choose-to-draw-power-from-gpio-vs-vddhMy setup: - nRF52840 Preview DK (though i have tried this on a newer version too) - 3.3V separate supply - DMM (Agilent 34465A) DK Connections: - SW9 is set to &quot;USB&quot; - SW6 is &quot;Default&quot; (doesn&#39;t make a difference either way) - USB cableen-USTelligent Community 13Wed, 24 Apr 2019 13:08:48 GMThttps://devzone.nordicsemi.com/thread/183493?ContentTypeID=1Wed, 24 Apr 2019 13:08:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6bab8c09-106d-4b27-a536-ed85d051285bJared<p>Hi,</p> <p>What voltage do you measure on the VDD pin when this happens?</p> <p>Best regards</p> <p>Jared</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/182777?ContentTypeID=1Thu, 18 Apr 2019 21:12:25 GMT137ad170-7792-4731-bb38-c0d22fbe4515:2e4ba7e7-3393-4b6d-beec-57bb00f5f45cDmitry<p>AFAIK, 52840 devkit has 3.0V buck regulator for VDD. If you supply any pin with voltage higher than VDD, it will draw power from this pin through internal protection diode. It&#39;s not a feature of nRF52840, any other chip would behave the same way (except ones with 5V-tolerant inputs).</p><div style="clear:both;"></div>