[SI-LIST] Re: Expresscard 1.0 Thermal Spec

  • From: "Andrew Ingraham" <a.ingraham@xxxxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 30 Aug 2006 10:42:43 -0400

It is also possible (again, only guessing) that either the 1.0A spec is the
peak current allowed (whereas 1.3W is average) ... or more likely, that some
of that 1.0A is intended for powering external devices that are connected to
the card.  Only 1.3W may be dissipated by the card itself, the remaining
power passes through and out the external port if it has one.

I would not expect 2W of radiated emissions to be allowed, unless this
some sort of RF transmitter, and not your usual wireless network type.


> I haven't seen Expresscard/34 spec. But I think if you can draw 1.0A from
> 3.3V, that means the effective resistance is R=V/I=3.3ohm, so the power loss
> is expected to be I^2R=3.3W. If the board can only turn 1.3W into heat, the
> left amount will either radiate or couple into its adjacent devices, which
> might cause EMI problem.

> >  hello, The Expresscard/34 spec says that you can draw 1.0A from 3.3V but
> >theboard can only dissipate 1.3W of thermal power.  Can someone clarify as
> >towhat this means? thanks in advance. LN

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