2007-06-18 15:16:48 · 6 answers · asked by wanabewest 1 in Computers & Internet ➔ Hardware ➔ Other - Hardware
the hub gets the power from the usb ports on the computer which then is sent to a usb devise. The hub asks the computer for more amps. that is why hubs can only have a curtain amounts of ports because there is a max amount of amps through the usb
2007-06-18 15:23:19 · answer #1 · answered by EJ 3 · 0⤊ 0⤋
USB skill is constrained to 500 mA (milliAmperes) complete, so in case you will use a number of USB contraptions this is ultimate to apply an AC powered hub to sidestep device injury and take care of the voltage and modern ranges on the USB ports.
2016-10-17 23:32:07 · answer #2 · answered by bruinius 4 · 0⤊ 0⤋
Depends if it's a powered hub or not. In short, if you need to plug the hub into the wall, the hub's powering your devices. If you don't need to plug the hub into the wall, all the power for the devices (and the hub) is coming from your computer. For a laptop, you almost always will want to use a powered hub.
2007-06-18 15:20:24 · answer #3 · answered by David Weekly 2 · 0⤊ 0⤋
The power still comes from the computer. the hub is just to be able to connect more things that are usb when you only have 2 or 3 slots
2007-06-18 15:19:15 · answer #4 · answered by SJ830 2 · 0⤊ 0⤋
Here is an answer I wrote for a very similar question:
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.
2007-06-18 15:32:03 · answer #5 · answered by Nathan S 2 · 0⤊ 0⤋
Usually, depending on the hub - small ones don't, big ones do - having a separate power supply.
2007-06-18 15:19:53 · answer #6 · answered by Mike1942f 7 · 0⤊ 0⤋