USB 3.0 provides the power supply via two connectors - a standard connector "type A" and powered connector "type B". Power supply via standard connector type A has similar properties as the USB 2.0 interface. There is for simplicity defined the equivalent load, in case of USB SuperSpeed interface is current of unit increased to 150 mA. USB interface contains several types of sources and appliances:
No device can realize power supply on VBUS wire at uplink port. Similarly as on the USB 2.0 interface to be the host and self-powered hubs provide protection against current overload. Restore of the normal functionality is possible without user intervention.
The highest allowable voltage drops within the bus topology are shown in the following figure.
Powered connector type B was introduced to allow for another device, such as e.g. printers, connection and power supply of other devices (e.g. adapters Wireless USB). This option eliminates the need for external power adapter. Power plug type B must be able to provide 5 volts in full current scale up to 1 A, provide protection against current overload, to deliver maximum energy regardless of the state of the terminal equipment. Terminal device providing the power supply through this connector must be low power and a terminal device, which is powered by a connector can not provide any standard plugs type A.