Re: [uCsimm] HV capacitors on the LAN transformer

From: John J. Cruz (casacruz@bellatlantic.net)
Date: Fri Aug 17 2001 - 14:10:57 EDT


The capacitors do not operate as zener diodes. The capacitors provide a low impedance
path to hi freq. noise. Also, if a spike with an amplitude of greater then 1 kV
appears across the capacitor, the capacitor could be damage to say the least. The
capacitor acts a filter.

jjc

Daniel Haensse wrote:

> Am Mit, 15 Aug 2001 schrieben Sie:
> > Folks, who can answer this...
> >
> > There is a LAN transformer on the ucsimm (VALOR- PULSE
> > ENGINEERING part PT4153S). On most Ethernet designs,
> > there are 2 1kV 0.01 capacitors connected to this
> > transformer on the ethernet side. On the ucsimm these
> > transformer pins are left unconnected. Question: what
> > these capacitors normally for, why they are missing
> > and is there any penalty for not having them?
> Those capacitors will discharge to gnd if the voltage is above 1kV.
> So if the LAN transformer can't stand the voltage anymore, on the uCSimm
> it will discharge to the uCSimm and may blow the ethernet controller or
> anything else that the high voltage enjoys to destroy.
>
> Dani
>
> >
> > I will really appreciate somebody answering this
> > question...
> >
> > Regards,
> > Dmitry Slepov
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Make international calls for as low as $.04/minute with Yahoo! Messenger
> > http://phonecard.yahoo.com/
> > This message resent by the ucsimm@uclinux.com list server http://www.uClinux.com/
> --
> **********************************************************
>
> Daniel Haensse
> Dipl. Ing. ETH
> Klinik fuer Neonatologie
> UniversitaetsSpital Zuerich
> Frauenklinikstr. 10
> 8091 Zuerich
> Switzerland
> Tel: ++41 / 1 / 255 5342
> Fax: ++41 / 1 / 255 4442
> email: daniel.haensse@alumni.ethz.ch
> This message resent by the ucsimm@uclinux.com list server http://www.uClinux.com/



This message resent by the ucsimm@uclinux.com list server http://www.uClinux.com/



This archive was generated by hypermail 2b30 : Sun Apr 07 2002 - 00:01:43 EST