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Thread: USB power in parallel
www.piclist.com/techref/power.htm?key=power
face picon face BY : email (remove spam text)(Olin Lathrop)



Tamas Rudnai wrote:
> Just found that USB Lava Lamp I have (got it from colleagues, I would
> not buy those :-))

Of course.  We understand.  It's from a "friend".

> So there is a 5V1W bulb in there, nothing else...
> That's 200mA, plus when it's cold it could be even bigger. There is
> no interface asking more power than 100mA, just using the power
> lines. Isn't it violating the specs?

Yup, and you won't likely find the official USB logo on the plug.  It will
probably work fine (within the limits of whatever "fine" might be for a lava
lamp) on most desktops.  It will fail to work correctly on computers that
tightly manage their USB power, and then you couldn't blame the computer.
Try it on several laptops.  They can be more picky about USB power to
carefully manage battery drain.


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