The nRF52840 DK has a 5 V boost regulator.
It gives a stable 5 V output from the following sources:
- USB connector J2 for the interface MCU
- USB connector J3 for the nRF52840 System on Chip (SoC)
- Lithium-polymer (Li-Poly) battery connectors J6 or P27. Connect only one battery at a time.
- VIN 3–5V pin on P20
Each source has a reverse protection diode to prevent current flowing in the wrong direction if multiple sources are connected at the same time.
Figure 1. 5 V regulator and protecting diodes