RAK19007 + RAK4631 - USB and J12 VDD can be connected at the same time?

[pico (pierluigi colangeli)]

Power related question:

I am providing the core with externally regulated 3V3 on the VDD pin of the board (J12 - pin 1).

According to the schematics of the board (RAK19007 - fig.15), it seems that there is no mechanism to turn off VBUS while 3V3 are fed to the core. Am I right?

Alternatively, if I supply regulated ~4V to the battery pins and desolder the TP4054, can USB programming and external power source cohexist?

Before releasing magic smoke, I’d like to have your confirmation.

Thanks

[beegee (Bernd Giesecke)]

The RAK4631 is designed to be supplied by two voltages, VBat and 3.3V from the voltage regulator.

Powering the RAK4631 only from 3V3 can work, but will cause a higher power consumption.

About your second proposal, it would be better to use the “Green Power” connector P2 to supply a regulated voltage with up to 5.5V to supply the WisBlock independent of the USB connector. There is no need to desolder the TP4054 in this case.

I am using that solution in many of my test devices that I built and that are not powered by a USB cable, but by an simple 5V output wall-plug.

[pico (pierluigi colangeli)]

sounds good!

Thanks for your help