At 11:31 AM 3/11/2012, you wrote:
>On Fri, Mar 9, 2012 at 12:58 PM, Herbert Graf <hkgraf@gmail.com> wrote:
>
> > "Integrated Magnetics" has nothing to do primarily with noise
> > suppression. Ethernet requires a transformer between the MAC and the
> > actual jack.
> >
> > Traditionally this was always done by an external part. Look at pretty
> > much any network card and chances are you'll see the transformer, it's
> > easy to spot.
> >
> > To reduce costs, manus started putting the "magnetics" into the jack
> > itself. This results in a slightly larger jack, but one less part to
> > source, route for and mount.
>
>My wife, also a computer "geek" but without an EE inclination was asking
>me why anyone would design with a jack without built-in magnetics these
>days.
>
>Could anyone clue me in?
>
>Thanks,
>    Bill

To save a bit of money. The combination of an external transformer and a
passive jack is still a bit less costly (used to be a LOT less costly,
but the integrated ones have come down a lot in cost). Putting it in the
can costs more and probably involves as much _total_ labor but saves on
the footprint and PCB assembly costs.

Of course there are also plenty of applications for RJ45 jacks that don't
involve Ethernet.

--sp

Spehro Pefhany --"it's the network..."            "The Journey is the rewar=
d"
speff@interlog.com             Info for manufacturers: http://www.trexon.co=
m
Embedded software/hardware/analog  Info for designers:  http://www.speff.co=
m



--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.