The charger board is a separate little board offered by Evolv to provide on-board battery charging, a function which is not integral in the dna controller itself. The charger board has the micro-USB socket on it. It's mounted at the very bottom of the XPV. Sorry, I'm not taking my XPV apart again this evening to show it to you in situ, but here's a picture of it from Evolv's website:
