nRf52840 Dongle not Booting with external power

[TasosR]

I am prototyping something using the nRf52840 USB Dongle.

Dongle works with the power supply from the USB

BUT doesn't work by applying power to the VBUS and GND even-though those two pins are connected to the power supply of the USB port.

I tried 3.7Volts from a Li-Po battery and 5Volts power supply but none of the works.

nRF52840 specifications manual describe that the supply Voltage should be 2.5-5 Volts with the value of 3.7V as typical...

[haakonsh]

That should work the VBUS pad should be connected to VDDH. I'll try to reproduce your issue when I get back from my business trip early next week.

Do you have a scope of VBUS? I'd like to see the rise time and curve of the voltage supply.

[TasosR]

EDIT: This happens only using another bootloader for this device (https://github.com/adafruit/Adafruit_nRF52_Bootloader) and not with the original bootloader ...

[haakonsh]

What exactly do you mean by "doesn't work"? We need more specifics. 

You should also open a ticket with adafruit.