Need to bridge SB12 to power eval board with external supply

[Torsten Robitzki]

Hello,

I have two brand new nRF52 DK eval boards version 2.0. On both boards, the reverse charging diode D8 is missing. That diode is required to power the board externally. Is this just coincidence that this diode is missing on both boards? The DK documentation in the info center does not include the version 2.

Note: the solder bridges are rather small and placed directly beside the diodes, which requires a very steady hand to solder them. On version 0.9.0 this looks way more comfortable. 

best regards

[Kenneth]

I can check with the person that have done the layout, however he is currently out of office. I will update when I hear back. It might be that they have done it this way to avoid the diode voltage drop when using external power.

Kenneth

[Torsten Robitzki]

Hi Kenneth,

thanks for looking into that. But in this case, one would definitively have to close the solder bridge to power the board externally. Would have been easier (from a user perspective) to leave the solder bridge out (aka close it).

best regards,

Torsten

[Kenneth]

Hi,

I have received more information about the circuitry, this should work without the diode as described in the attachment.

pca10040_schematic_sheet7_battery_power-up.pdf

Best regards,
Kenneth

[Torsten Robitzki]

I've checked that with the second board I have and there, powering the board externally works without closing the solder bridge. For the first board I had to close the solder bridge to see any voltage at TP14. Maybe the other diode was broken or what ever :-)

Anyway, thanks for taking the time to look into this!

best regards,

Torsten