2007-05-24 09:19:42 · 4 answers · asked by deliabrito1616 1 in Computers & Internet ➔ Hardware ➔ Add-ons
All USB devices are one of two "power" types: Bus-powered and Self-powered. Self-powered devices do not consume power from the bus, but from their own wall brick. Hubs are no exception - there are bus-powered hubs and self-powered hubs.
Bus-powered devices are subdivided into Low-power and High-powered devices. Low-power devices are limited to 100 mA, and high-power devices are limited to 500 mA.
USB hubs that are bus-powered are high-power devices (500 mA) and can only have low-power devices attached (100 mA devices). In fact, they can only have a maximum of four (4x100 mA) devices, with the last 100 mA used by the hub itself. That's why a bus-powered hub has only 4 ports.
In order to plug a high-power device into a hub, or more than 4 devices, the hub must be self-powered so that it can provide more than 400 mA to its attached devices.
So, a self-powered 7-port hub can have 7x500 mA devices attached, which is why it has that huge brick for you to plug in.
If you have a high-powered device, like, say, a disk drive, you cannot plug it into a bus-powered hub and expect it to work. The OS will detect this condition and complain. You must plug it into a self-powered hub.
You can always plug a self-powered device (one with a wall plug) into any hub, because it draws no power from a hub.
The root ports on a PC are powered by the main power supply of the computer, so they are considered to be ports of a self-powered hub.
Hope this helps :)
N.
2007-05-24 10:20:03 · answer #1 · answered by Nathan S 2 · 0⤊ 0⤋
A USB "powered" hub is one which will come with its own A/C adapter that would plug into the wall to supply the necessary power to the device. This is necessary in many because it requires more power to run the hub (and the devices connected to the hub) than the hub can draw from the pc from the USB cable alone.
2007-05-24 16:23:54 · answer #2 · answered by truextremeicon 3 · 0⤊ 0⤋
It plugs into the wall so that it can give more power to USB devices. There are also hubs that don't plug into the wall and just draw power from the USB port they plug into.
2007-05-24 16:24:20 · answer #3 · answered by Yoi_55 7 · 0⤊ 0⤋
both powered and non powered share information the same way the difference is this...
"not powered" = the hub gets its power for your usb devices from the computer.
"pwered" = the hub gets its power for your usb devices from the wall.
2007-05-24 16:32:34 · answer #4 · answered by viper 1 · 0⤊ 0⤋