Hey guys and gals, I have a quick question about power supplies. I'm about to purchase a 5V/2A Wall charger. For my specific project, I have a USB connected to the mBed for Serial Communication so it's getting power from there. I then have ANOTHER USB cable powering something that requires 3.3V, and then I have a wall charter that is 5V/.3A. I want to get rid of the 2nd USB cable and replace the .3A -> 2A.

My question is this: Can I take the 5V/2A charger and put it into Vin on the mBed with the USB connector in as well? Then can I use the 3.3out and Vout to power my other items? I don't know what happens if you power the mBed from USB & Vin and don't want to damage it.

Thanks!

You can connect the PC USB cable for serial comms and a separate Vin at the same time without problems. The mbed itself will be powered from either USB or Vin or both. The 3V3 Vout on pin 40 is available whenever mbed in powered. However, the maximum current is limited. Dont draw more current than say 200mA when you have only USB power and maybe go a bit higher when you have Vin available. On Vout you cant go anywhere near the 2A that your charger can supply. If your external device needs that much power your will have to use a separate offboard regulator.

Also be aware that the Vu (5V, pin 39) is ONLY available when you have the USB connected.

Thanks for the information! I'll try to find a 3.3V regulator and it should fix everything.