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Old 04-28-2010, 09:59 AM   #15
theducks
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Quote:
Originally Posted by Solicitous View Post
I was under the assumption that it was 500mah per USB hub, so if you have 2 USB ports on your computer running off one internal hub, the 500mah was shared between the ports. So if you are running a USB mouse drawing say 50mah and you plug in your PEZ, that would leave 450mah for the PEZ to draw on.

I could be wrong but that was the impression I got with USB, mah output is per hub, not port.
The spec is per Port, but you are not alone with the per hub thinking.

per hub is lots cheaper to build

The Point of Sale Industry wanted more power and more voltages to run all that stuff you see at the cash-wrap.
Enter USB+Power
That added a side-car to the USB plug with: More 5V current and 12V (green) for displays, big scanners, credit terminals and 24V (red), typically printers .
Some consumer devices now come with a 5/12V port version that will run an external (Optical) Disk drive.
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