nRF52840 Preview DK v0.9.x

nRF52840 direct supply

It is possible to source the SoC directly from a source without powering the rest of the board from the same source.

The external source can be connected to the external supply connector (P21) and the VEXT->nRF switch (SW10) put in the ON position. The nRF power source switch (SW9) must be in the VDD position, and the allowed voltage range is 1.7–3.6 V.

Figure 1. VEXT->nRF switch (SW10)
VEXT→nRF switch
Since it is only the nRF52840 SoC that is supplied from this source, it is recommended to supply the VDD domain from a different source (coin cell battery or USB) to prevent the pins of the SoC to be connected to unpowered devices. To prevent leakage due to voltage differences, the board should be set in the nRF only mode, see section Operating modes.
Important: To reduce trace length and parasitic components, the external memory is connected to the SoC directly instead of using analog switches. It is recommended to cut solder bridges to avoid leakage, see section External memory.