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Unread 09-03-2010, 11:49
Dave Flowerday Dave Flowerday is offline
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Re: Powering your USB Hub at Competition

Quote:
Originally Posted by eagle33199 View Post
There should be no difference, according to the USB standard. In order for USB devices to work on an extremely wide variety of machines (from laptops to desktops, Dell to HP to Apple, etc) the standard dictates exactly how the USB port should act, including how much power is available, the transfer rate, protocol, etc. For any device with a USB output, that standard is going to be followed.
Actually, there could be a difference. The USB standard indicates that a device may initially draw only 100mA from the port. The device must request, via transfer on the bus, if it wishes to exceed that limit, and may request up to 500mA. The host can deny this request if it wants (due to not enough power available etc). I've never seen this actually happen, but certainly seems plausible that a small netbook with a tiny battery might deny >100mA requests when running off battery.