Hi!
I would like to completely isolate the nRF52840 on the Preview-DK (2017.32) on hardware level.
Scenario
I would like to power the nRF IC with the external supply pins without having to attach a USB cable. When I apply power to the external supply pins, setting SW10 (VEXT->nRF) to ON and SW9 (nRF power source) to VDD. I should only be supplying the nRF if I look at the schematics.
But if you look at the image there is a power meter connected to the external supply pins and with USB the current draw is 'normal' 25uA but when I unplug the USB the current draw is around the 3,75mA. I think the problem is that there are leak currents flowing through the nRF to the programmer and attached components.
I know it is possible to set switch SW6 to "nRF ONLY" but then you still need to connect a USB cable to power the electric switches. So I need a real hardware solution.
Looking at the schematic I noticed that I can cut SB10 to SB16 to disconnect the flash and cut SB50 to SB57 to disconnect the programmer, but there is a problem here. The schematics I have say that they should be all connected, but the PDK I have has no SB16 and SB50 to SB57 are disconnected by default.
So... is there a possibility to completely separate the programmer from the nRF without de-soldering the whole programming area?
I'm curious to know!
Best regards,
Alpha
