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From: "Michael A. Terrell"
Subject: Re: *standard* VGA sync levels ?
Date: Mon, 02 Dec 2002 12:16:28 -0500
Organization: Have you seen my bench? No, really! Where is it?
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References: <email@example.com> <firstname.lastname@example.org>
fred bartoli wrote:
> John Jardine a écrit dans le message :
> > fred bartoli wrote in message
> > news:email@example.com...
> > > Hello,
> > >
> > > The fire brigade (I) have to design some protective device (will be a
> > > of dongle) that will be insterted between the video output and the
> > > cable to prevent a badly designed video output (our nice work) to
> > "randomly"
> > > latchup in fields (about 5% every two weeks... eh eh, not so bad).
> > >
> > > I'm OK with the RGB lines (levels are low) but the HSYNC and VSYNC
> > > are typically 5V levels and I *have* to be ensure clamping under the
> > > VCC level (the chip seems pretty sensitive and have no specs) which
> > no
> > > room at all if taken abruptly.
> > >
> > > So I need the minimum *standard defined* level a video card has to put
> > > sync signals.
> > >
> > > (didn't manage to find anything useful outof google)
> > >
> > > Anyone has a pointer or the values on top of his hat ?
> > >
> > > thanks,
> > > Fred.
> > Had a bit of trouble figuring the question ;-).
> > (thought VGA was -all- logic levels.
> > There's little VGA info out there but I found this a few weeks ago from
> > epanorama.net. Don't know if it's relevant ...
> > regards
> > john
> > _____________________________________________________________________
> < Deleted some stuff from epanorama>
> Thanks John.
> Maybe I should have have made it more clear (see my answer to Ian) but I'm
> all but a PC related digital stuff design guy. In clear, almost all I knew
> is that a VGA (or what ever todays standard is called) plug is a HDE15
> (thanks Michael) plug, and now that the video levels are 0.7V nom.
> However, the first VGA video cards I remember were 16 colors, so I don't
> think the video colors were logicl levels (only 8 colors). I rather think
> the all digital was the CGA standard (only 8 colors), but maybe I'm wrong on
CGA and EGA were both TTL levels, while VGA and SVGA are analog
video. You can find a lot of information by downloading the data sheets
on the current crop of SVGA video chipsets.
Michael A. Terrell
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