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.
Note: The maximum current for USB 3.0 is 0.9 A.
The output of the regulator supplies the SoC and the LEDs. The USB power connection (VBUS) is also available along the board edge. Next to VBUS, there is a connection point for VDD OUT, which is the output of the nRF52840 SoC high voltage regulator. For maximum power draw from this pad, see nRF52840 Product Specification, and take into account the power draw of the onboard nRF52840 and the LEDs.
Figure 1. USB power connection (VBUS) and SoC high voltage regulator output (VDD OUT)
By using the on-chip high voltage regulator, the VDD voltage level can be set in the REGOUT0 register in UICR. See nRF52840 Product Specification.