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Recently upgraded an old iPhone 3GS to the iPhone 5. Shortly after plugging in the iPhone to a new Windows laptop (usually under 10 minutes), the entire USB hub will reset, disabling all connected devices.

(A USB thumb drive once was the sole survivor, and continued operation even though an external hard drive and USB mouse shut off.)

The laptop is on AC power and has two discrete hubs, one USB 3.0, the other USB 2.0. The same thing happens to either hub, and in both cases, the other is unaffected.

As the 3GS never caused this issue, I am assuming the iPhone 5 draws more heavily on the USB power.

Is there anything I can do to eliminate this issue, other than get an externally-powered hub? (Which I plan to do!)

Update: If I plug the iPhone in fully charged, there seems to be no issue. This seems to indicate that it is indeed related to power draw.

Screenshot of the USB hub properties when the phone is fully charged: enter image description here

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Are you running an external hard drive off of an uncharged hub? Does the hard drive have its own power source? This piece is confusing me. – Daniel Lawson♦ Oct 2 '12 at 16:42
@DanielLawson - The hard drive is externally powered. It does not shut off, it merely loses connection to the computer, along with the mouse plugged into that hub. – Unsigned Oct 3 '12 at 2:41
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I would assume that even if the hub theoretically can output seven times 500 mA, the total output of your laptop USB port is somewhere around 500 mA itself. Thus, one iPhone alone is just enough to bring it down. – myhd Oct 30 '12 at 14:45
Does the hub have its own power source or are all your devices sharing the 500 mA @ 5 V from the computer? – Kevin Chen Jan 7 at 7:30
@KevinChen - When I spoke of a "hub" above, I was referring to the internal "hubs" on the motherboard. The USB cable is plugged directly into the laptop. – Unsigned Jan 12 at 6:11
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1 Answer

up vote 1 down vote

Wow, 7 USB ports is a lot for a laptop!

Because (as you mentioned) the iPhone and iPad consume above-standard amperages, they can sometimes cause issues such as this. Most USB controllers are dynamic enough to simply provide a standard amount of power to just the iPhone, but there have been a couple of cases I've seen where the hub crashes as you're describing. When the hub provides a USB-standard amperage to the device, the device will indicate that it is not charging (though explicitly indicating that it is plugged in).

I'm interested to know what model laptop you're using as it may be a known issue for the corresponding USB controller.

As for a fix, you can see if there is updated firmware for the controller. If those are unavailable or don't resolve the issue, I suggest getting a powered external USB hub. Using one will eliminate the power strain on the motherboard and will probably extend the life of the PSU.

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