http://www.microsoft.com/taiwan/whd...s/USB/hubs.mspx

參考微軟網站如上, 截錄其中一段如下 :

"A user can plug any bus-powered USB device into any port on a self-powered hub, and the device will always have enough power to function. The power needed by a bus-powered USB device in order to function can range from a few mA up to a maximum of 500mA."