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How much current can I get from an Xbox's USB port? Answered

Additionally, I need to boost the five volts coming out to ten or twelve. I have a schematic I think may work, I believe it's a 1070 voltage booster. I need to get about twelve volts and 0.11 amps, so it looks I need to pull at least 0.264 amps from the USB port. Can I do this? Does anyone know anything about voltage doubles? Thanks a lot for your help.


Can't "double" DC....

Also, a USB port is only supposed to give you 100mA, unless it can negotiate a higher current with the slave.

Is the 100mA for USB1? or is my memory just wrong? (see other post on this topic)
Or do USB2 just have to allow for negotiating upto 5mA?

It was the limit for one, but, for shame, I don't know about 2....I shall take a look....

"A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0." (souce http://en.wikipedia.org/wiki/Universal_Serial_Bus#Power)

So that is where i got it from i guess. If a device can request all 5 loads then i am right, otherwise i am partly wrong (it can still provide 5mA, just not to one device).

Thank you, that helps a lot. Thank you.

Yeah, that 2nd paragraph is a mess, both in facts and figures and in meaning - just ignore that part :-)

I then assume (sorry if i make a 'behind' out of you) that you happen to know the Xbox is USB1 (That piece of the spec should be reasonably easy to find, as should USB2 cert. amp requirements) But it may make sense that the orignal Xbox is USB1 since it is starting to get rather old.

As Steve says below the unit load is 100mA for USB1&2 and 150mA for USB 3. The USB spec allows a single USB port to support 5 units or up to 500mA. The 100mA is pretty much the minimum amount of power a USB port is suppose to offer. But more then 500mA is typically available to be spread across multiple ports. So the Xbox should be able to support 500mA through a single port but it could be less.

As for your idea os boosting the power output of the USB port... Since your going to be inside the system already and making additions and modifications like that why not tap into the 12V rail of the Xbox's power supply and not worry with the USB ports. 110mA of additional load on the 12V rail shouldn't be a problem.

I'm not modifying anything inside the Xbox- everything is external. It goes Male USB---->Voltage doubler---->Fan. Although it would be tremendously useful to have external 12 vdc ports on the back or something.

Jeez- I know! I couldn't find any! Anywhere! All they had was twelve volt! I've made my decision and I choose to use a twelve volt fan!

Ahem. Excuse me.

Exactly. Now that I've started down this complicated path, it's gonna be a little hard to bail, so all I need right now is a means to power the fan.

I have a schematic that uses an lt1070 to boost the voltage, but I can't seem to find the part itself anywhere. Anyone know where I might be able to find one?

Yes, "we" solved this question below - regarding the amps pull

Why the USB port? Why not tie into the Xbox's 12V rail directly and forget about the voltage booster.


5 years ago

Does the Xbox use USB2? If my memory is correct; to be USB2 certified you need to allow for .5amps