Bus-Powered Devices

Bus-powered hubs use power from the USB bus to which they are connected, to power devices connected to them. Special care must be taken to not overload these hubs, since the power these hubs offer to their downstream devices is limited.

• Do not cascade bus-powered hubs. For example, do not connect one bus-powered hub to another bus-powered hub.

• Avoid connecting bus-powered devices to bus-powered hubs, except for low-speed, low-power devices, such as keyboards or mice. Connecting high-powered devices such as disks, speakers, or microphones to a bus-powered hub could cause power-shortages for all devices connected to that hub. This scenario could cause these devices to behave unpredictably.