Hello,
According to the reference designs of the nrf52833, VBUS should be connected to GND when the USB peripheral is not used. We have a design in which the device is normally powered by a battery, but USB can be used from time to time to communicate with the device.
While powered by the battery we do not want any spurious current to flow through the VBUS pin or to be caused elsewhere by not grounding the pin properly. According to our measurements the best performance is when it is connected to GND, but since the USB might be connected eventually we cannot route it perpetually to GND.
Do you have any suggestions here or any figures of which the consequences (impact on current consumption) are leaving the VBUS open (actually with a 4.7uF cap) when the battery is used?
For reference, we are using the DWM3001C module, which has a 4.7uF capacitor attached between that pin and GND:
https://www.qorvo.com/products/d/da008300
DECUSB is also internally connected inside the module to GND through a 4.7uF cap, and this cannot be changed, in case it is relevant.
As I see, for instance, in the nrf52840dk VBUS is also open (with the cap) when the USB is not connected.
Best,
Antonio
