http://en.wikipedia.org/wiki/USB#USB_3.1:
The standard is backwards compatible with USB 3.0 and USB 2.0. Utilizing five power profiles defined in the USB Power Delivery Specification, it will allow devices with larger energy demands to request higher currents and supply voltages from compliant hosts, up to 2 A at 5 V (for a power consumption of up to 10 W) and optionally up to 5 A at either 12 V (60 W) or 20 V (100 W).[25]
Zařízení si může vyžádat vyšší napětí.
Počítá s dodávkou energie v režimech 2A*5V,5A*12V a 5A*20V.