11 years ago.

Power supply and mbed USB connection

Hi all!

Just a short question. I wan't to supply the board (and so the mbed) via its DC jack. But I also would like to connect a PC to the mbed-USB connector sometimes to get some serial feedback from my application. (Hot-plug)

Since the board (and the mbed) both can be powered via mbed-USB, the two supplies would both feed voltage...

My question is if this is supposed to work or can I damage the board or the mbed with this?

TIA. Salut, J"org

Question relating to:

1 Answer

11 years ago.

This will be no problem. Both voltages are send over diodes. If the external voltage is higher than the USB voltage no current will flow from USB. The diodes act like a valve.

Accepted Answer

Thanks Peter!

Yes, I knew that about the Diodes. I saw them in both schematics. But I wasn't quite sure about how the (many) voltage regulators would react when they are "driven from the wrong side".

Another point I just found out and which could be handled in "version 2" of this board: ;-)

If I supply this board via DC jack, I won't get a regulated 5V supply on any connector or on the mbed pins (like VU). I need this voltage for CAN transceivers...

Of course I can fetch 5V (exactyl 5V - U_fw_bat60a) from USB_A but that's not very nice. :-)

Albeit, thank you very much again! J"org

posted by Joe SL 09 Mar 2013