We have the device, where 2 power supplys can be applied.
One of them is external regulator with 3.3 V output. We used it for additional load in our device.
Another one is a 5V from USB - we want to use nRF52840 as peripheral device to conrol external load.
As we understand 5V from USB should be connected only on VBUS. It's required only for signaling interface.
The USB peripheral has a dedicated internal voltage regulator for converting the VBUS supply to 3.3 V used by the USB signalling interface (D+ and D- lines, and pull-up on D+). The rest of the USB peripheral (USBD) is supplied through the main supply like any other on-chip feature. As a consequence, both VBUS and either VDDH or VDD supplies are required for USB peripheral operation.
At the same time we connected external regulator on VDD. See image below.
We need to be sure that this configuration will work.
The main question here, what will happen when external regulator provide power on VDD and REG0 provide power at the same time.
