>Andrej wrote:
>.........
> >the first point where to start with protection circuits for analog
>signals
> >is the signal bandwidth. From that you can calculate easy the
> >filter cut-off frequency on input. Filters could be realized from simple
>R
> >and parasitic capacitance of tranzsorbs. If the capacitance of TZB is to
> >high, then combination of fast schottky-diodes could be fine. If you need
> >more protection, then you must use on input IC with ESD protection on
>input.
> >Maxim or Linear do such IC, but costs little bit more.
> >
>
>
>I looked at this a little further since mentioning the transzorbs
>yesterday. The lower voltage devices, which you would want to use
>to help protect chips, have a substantial parasitic capacitance
>- about 800 pF [much lower for higher V types]. Therefore they
>are not going to be very useful for "high" datarates, except
>possibly as part of a low-pass filter designed especially for
>the app.
>
>Xc = 1/[2*pi*F*C] = 1[2*pi*100Khz*800pF] = 1900 ohms @ 100Khz
>
>- danM
>

Dan, when you need protect High-Speed lines like satelite comunication,
there are other tricks to do that. I just wanted to give a point, where to
start the design. And it's allways signal bandwidth. When transzorbs are not
useable, then other circuits may do the same job. What do you think?

Andrej

p.s.: By the way, EMC is sometimes nice game with ghosts and old bad witchs,
mostly bewitching everything they can. Knowing some kinds of conjuring
tricks, sometimes it's whisky, really very helpfull, you kill them.

_________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

Share information about yourself, create your own public profile at
http://profiles.msn.com.

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu