https://devzone.nordicsemi.com/f/nordic-q-a/95660/nrf52840-being-powered-via-uart-pinsHi, I have a NRF52840 that has pins P1.07 and P1.04 connected to a FTDI cable. The GND is also connected to the FTDI cable. Nothing else is connected and the device powers up...... Does anyone have an explanation for this behavior? Cheers, Clancy.en-USTelligent Community 13Fri, 13 Jan 2023 06:35:07 GMThttps://devzone.nordicsemi.com/thread/404686?ContentTypeID=1Fri, 13 Jan 2023 06:35:07 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3cdae8b9-8877-49e8-be4b-004a276ded42Priyanka<p>Hi Clancy,</p> <p>Please do make sure that the GPIO pins have 0V when the device is powered off. You can refer the <a href="https://infocenter.nordicsemi.com/topic/ps_nrf52840/abs_max_ratings.html?cp=4_0_0_8">absolute maximum ratings</a> and see that the I/O pins ratings are a maximum of VDD + 0.3V. So, when system off, VDD is 0V and this makes anything greater than 0.3V connected to the GPIO, directly connected to VDD and thus device powers on.&nbsp;</p> <p>Best Regards,</p> <p>Priyanka</p><div style="clear:both;"></div>