Hardware description
In the Li-Po position, the high voltage regulator of the SoC is supplied directly from the Li-Po battery
connectors (J6 or P27). In the USB position, the USB high voltage regulator gets power from the nRF52833
USB connector (J3).
When the high voltage regulator is used, the VDD_nRF voltage can be set by the firmware of the SoC.
To make sure the rest of the DK has the same voltage level, the VDD of the DK is sourced by a regulator
following the VDD_nRF voltage when the high voltage regulator is used.
Figure 13: VDD_nRF voltage follower and switch
To make sure that the nRF52833 SoC is not powered when the nRF power switch (SW8) is OFF, two load
switches are used, one for the high voltage regulator (U23) and one for the USB supply (U22). These
switches are controlled by VDD.
8.3.5 nRF52833 SoC direct supply
It is possible to power the SoC directly from a source without powering the rest of the DK from the same
source.
This is done by connecting the external source to the external supply connector (P21) and sliding the
VEXT->nRF switch (SW10) to 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 14: VEXT->nRF switch (SW10)
Since it is only the nRF52833 SoC that is supplied from this source, it is recommended that the VDD
domain is supplied from a different source to prevent the pins of the SoC to be connected to unpowered
devices.
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