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USB ports typically provide anywhere between 5-6V.
If a laptop/notebook USB port is only producing between 4-5V;
What can be done to fix (i.e. boost/increase) the output voltage?

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  • Replace the motherboard
    – acejavelin
    Sep 14, 2016 at 23:27
  • @tjt263 - To what purpose ? The USB port seems to be operating within spec (USB does not go to 6 volts). If you have a USB device which is drawing to much power you need to fix the power issue for that device (I'm thinking along the lines of a USB hub pulling more then 0.5 amps - eg to spin a hard drive). In the case of something drawing more then 0.5 amps you need to supplement the power supply for that device. (Sometimes a Y cable can do this, otherwise the correct way would be with appropriate hardware which can take an additional source of power from the wall)
    – davidgo
    Sep 14, 2016 at 23:52
  • To what purpose? The USB port seems to be operating within spec. It's not. Otherwise; it wouldn't be an issue.
    – voices
    Sep 15, 2016 at 0:09

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Your measurements are too vague, they need to be more precise to determine if there is really an issue. You can't adjust the voltages, if there is a problem with the voltages it is a chipset issue and the motherboard in the laptop probably needs to be replaced. USB has very specific voltage ranges:

USB 2.0 - 5.0vDC +0.25/-0.60 @ 500ma load
USB 3.0 - 5.0vDC +0.25/-0.55 @ 900ma load

It is specified that devices configuration and low-power functions must operate down to 4.40 V at the hub port by USB 2.0 and that devices' configuration, low-power, and high-power functions must operate down to 4.00 V at the device port by USB 3.0.

More details on USB specifications are available here

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  • Your measurements are too vague, they need to be more precise to determine if there is really an issue. Well, I'm telling you outright; it's an issue. FYI: Pretty sure it's only USB 1.x but yeah, it does definitely get below ~4.40V. Although, my other laptop's bus produces output in excess of ~5.25V (up to ~5.69V) and my 5W iPad charger is currently peaking @ (actually seems to be fluctuating between) ~5.40V / ~5.44V.
    – voices
    Sep 14, 2016 at 23:59

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