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RE: VGA PDA alternative

From: "Tony Havelka" <>
Date: Thu, 8 Apr 2004 09:30:24 -0500

> Good idea.
> Our SMPS generates 5v @ 1Amp for the USB HOST ports.
> Then there's another switcher off that for the 3.3volt power=20
> for the electronics. We'll have over 3/4 amp available for=20
> USB devices or external devices from the 5-volt supply. We're=20
> tight on connector space, but not all pins are used on the=20
> VGA connector. Do any HMDs draw power from the DE-15 connector?

No and I would recommend to avoid putting power on the VGA connector.  =
Great
for HMDs, could prove disastrous when you plug a regular monitor into =
it.

> Another option is to change the power input connector to one=20
> with more pins to support power-out.

This may work. What about some post headers on the board and leave it up =
to
the customer to "remote" the power output with their own connector on =
the
end - if they need it?

> We know at least one HMD maker was looking at a USB dongle=20
> for controlling the display settings, and also for stealing=20
> power from the host. That would work without extra ports, but=20
> not many devices will run from that low a current level.

Good idea until you have another product that needs power on the bus as =
well
or if you have 2 ports and 2 devices hooked up already.  Where do you =
put
the 3rd?

-Tony

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