The nRF52840 Dongle can be powered from different sources.
Internal regulator
The default power supply of the nRF52840 Dongle is the USB interface. The USB interface supplies power to the on-chip high voltage regulator of the nRF52840 SoC.
External regulated source
The nRF52840 Dongle can also be configured to be supplied from an external regulated 1.8–3.6 V (max 50 mA) source through the VDD OUT connection point. To enable this, SB2 must be cut and SB1 must be soldered.