The nRF only mode disconnects the power supply, external memory, and LEDs of the interface MCU. It also disconnects the signal lines between the nRF52840 System on Chip (SoC) and the interface MCU using analog switches.
This is done to isolate the chip on the Development Kit (DK) as much as possible, and can be of use when measuring currents on low-power applications.
The power supply of the external memory can be changed to maintain operation in the nRF only mode. See External memory.
Figure 1. nRF ONLY switch (SW6)
