NRF52840 being powered via UART pins

[Clanc1]

Hi, 
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. 

[Priyanka]

Hi Clancy,

Please do make sure that the GPIO pins have 0V when the device is powered off. You can refer the absolute maximum ratings 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. 

Best Regards,

Priyanka