On Fri, 2010-11-12 at 21:52 +0100, Wouter van Ooijen wrote:
> > Partly the "real" USB spec, not Apple's made up one. says a Max of
> > 500mA. not 1000mA.
>=20
> IIRC it states that 500mA is the maximum *a device can count on* to get.=
=20
> It is **not** a maximum that the host is guaranteed not to exceed! IIRC=20
> the text is something like "the host shall limit the current to  safe=20
> maximum".

Very true, it's a minimum spec, a port is "guaranteed" to be able to
supply up to 500mA, given everything else is right.

In real life, many ports ARE current limited, cheapers ones usually
around 1A (I've seen polyfuses used most frequently). Some will only
supply 500mA, some have NO limit (the cheapest cards I've seen have
polyfuse footprints, but a solder bead across the contacts), and will
supply whatever the power supply in the host is capable of supplying.

TTYL

--=20
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