Read this: http://www.national.com/an/AN/AN-1085.pdf


-2.7V spikes for 200 ns
"Masoud Naderi" <naderimisc@yahoo.com> wrote in message
news:2ba3bbea.0312210846.3ed95f90@posting.google.com...
> Hi,
> I measured ground voltage difference between two side of cable, it was
> very small (<0.1V). However I like to install a low impedance( againt
> high frequency noises) cable between two racks, but I have not
> acceptable reasons for this!
> please guide me on this.
> regards.
>
>
> "tbx135" <tbx135@msn.com> wrote in message
news:<%DtEb.42912$yp5.14836@newssvr31.news.prodigy.com>...
> > This sounds like a grounding problem, whose LVDS drivers are you using?
> >
> > "Masoud Naderi" <naderimisc@yahoo.com> wrote in message
> > news:2ba3bbea.0312152232.5d87d9d2@posting.google.com...
> > > Hi,
> > > Our LVDS Drivers failed when their power supply starts(it has soft
> > > start feature). On some boards only positive output or input of
> > > differential side failed (probably because of high current sourcing in
> > > failure mode).
> > > I checked power suppply yesterday and found some negative (-2.7v) but
> > > very narrow (200ns) spikes on power supply rail. I think it is one of
> > > the problems. LVDS drivers are from TI and spikes below -0.5 damage
> > > them. I look for more problem, e.g. grounding and ...
> > >
> > > here are some shematic of our system:
> > >
> > > LVDS+/- <-............3meter twisted-pair cable...............->
> > > LVDS+/-
> > > GND ----------------------------------------------------------> GND
> > >
> > > regards
> > >

Hi,
I measured ground voltage difference between two side of cable, it was
very small (<0.1V). However I like to install a low impedance( againt
high frequency noises) cable between two racks, but I have not
acceptable reasons for this!
please guide me on this.
regards.


"tbx135" <tbx135@msn.com> wrote in message news:<%DtEb.42912$yp5.14836@newssvr31.news.prodigy.com>...
> This sounds like a grounding problem, whose LVDS drivers are you using?
> 
> "Masoud Naderi" <naderimisc@yahoo.com> wrote in message
> news:2ba3bbea.0312152232.5d87d9d2@posting.google.com...
> > Hi,
> > Our LVDS Drivers failed when their power supply starts(it has soft
> > start feature). On some boards only positive output or input of
> > differential side failed (probably because of high current sourcing in
> > failure mode).
> > I checked power suppply yesterday and found some negative (-2.7v) but
> > very narrow (200ns) spikes on power supply rail. I think it is one of
> > the problems. LVDS drivers are from TI and spikes below -0.5 damage
> > them. I look for more problem, e.g. grounding and ...
> >
> > here are some shematic of our system:
> >
> > LVDS+/- <-............3meter twisted-pair cable...............->
> > LVDS+/-
> > GND ----------------------------------------------------------> GND
> >
> > regards
> >

This sounds like a grounding problem, whose LVDS drivers are you using?

"Masoud Naderi" <naderimisc@yahoo.com> wrote in message
news:2ba3bbea.0312152232.5d87d9d2@posting.google.com...
> Hi,
> Our LVDS Drivers failed when their power supply starts(it has soft
> start feature). On some boards only positive output or input of
> differential side failed (probably because of high current sourcing in
> failure mode).
> I checked power suppply yesterday and found some negative (-2.7v) but
> very narrow (200ns) spikes on power supply rail. I think it is one of
> the problems. LVDS drivers are from TI and spikes below -0.5 damage
> them. I look for more problem, e.g. grounding and ...
>
> here are some shematic of our system:
>
> LVDS+/- <-............3meter twisted-pair cable...............->
> LVDS+/-
> GND ----------------------------------------------------------> GND
>
> regards
>

Hi,
Our LVDS Drivers failed when their power supply starts(it has soft
start feature). On some boards only positive output or input of
differential side failed (probably because of high current sourcing in
failure mode).
I checked power suppply yesterday and found some negative (-2.7v) but
very narrow (200ns) spikes on power supply rail. I think it is one of
the problems. LVDS drivers are from TI and spikes below -0.5 damage
them. I look for more problem, e.g. grounding and ...

here are some shematic of our system:

LVDS+/- <-............3meter twisted-pair cable...............->
LVDS+/-
GND ----------------------------------------------------------> GND

regards

Masoud,
    Can you tell me more about the failure mode?
NJ


"Masoud Naderi" <naderimisc@yahoo.com> wrote in message
news:2ba3bbea.0312150037.12810136@posting.google.com...
> Dear all,
> Please tell me how LVDS drivers with cables can damaged?
> Possible cases are:
> 1 - Power supply under/overshoots.
> 2 - ESD on cables.
> 3 - Missing hot-plugging. e.g. connect GND, then signal, then power.
> 4 - Killer spikes on power supply rail or input/outputs.
> 5 - ?
>
> Regards.

Dear all,
Please tell me how LVDS drivers with cables can damaged? 
Possible cases are:
1 - Power supply under/overshoots.
2 - ESD on cables.
3 - Missing hot-plugging. e.g. connect GND, then signal, then power.
4 - Killer spikes on power supply rail or input/outputs.
5 - ?

Regards.