nrf52840 DK non-USB power source

[Mahmoud]

Hi - I am trying to power the nrf52840 DK from a non-USB power source and it does not power up, or powers up and down immediately. I tried the coin battery (with SW9 to VDD), the Li-Po (tried J6 and P27 with SW9 to Li-Po), and the external source (P21 with SW9 to VDD); they all don't work. I have revisited the schematic and the documentation and they show that any source should work without modification (i.e. jumper). Could you correct me if I have done something wrong or am missing something?

[Stian Røed Hafskjold]

The power LED is connected to the debug IF on the DK, so if the USB cable is unplugged the debug IF is not powered up and the power LED is not lit. So your board might be powered up even though there is no indication of it.

Can you measure the voltage on VDD_nRF on P20? If this is close to 3V the chip is probably running just fine.