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How to choose transformer for LVDS?

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kobik

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hi,

how to chose transformer for lvds? all the transformer
i found are for LAN or telecomm.

can i use transformer for Ethernet (i use CAT5)?

thx,
kobik :?:
 

mr_ghz

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lvds isolation

Hi kobik,

why do you want to transform your LVDS-signals? - Normally there is
no galvanic isolation!
If you really need an isolation a 'standard' Ethernet transformator (even
a 100MBit one) can not be used. The frequencies on LVDS can be much
higher and the impedance does not mach.
A better (but expensive) solution would be to make a galvanic isolation
before the LVDS driver/receiver and to supply them with a DC/DC
converter.

Greets
 

kobik

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lvds isolator

thx,

even if my LVDS freq=20-60MHz

kobik
 

silicon

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isolating lvds

What is the mean of transformer?

Is it mean translation differential singal (LVDS) to single end?

Silicon
 

mr_ghz

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lvds galvanic isolation

Hi kobik,

Again: normally you do not use a transformer on LVDS line, even if it's
possible (in some circumstances). So if you don't have a big reason
(common mode problems, using coax-cables) you should use a direct
coupled LVDS.
In the case of such low bitrates as you wrote (below 100MBit/s) I think you
could try it with an 100MBit Ethernet transformer. The missmatch in
termination won't be very critical.
For further information look at the national homepage, they have a lot
of design rules for LVDS lines.

Bye
 

trifilinux

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transformer coupled lvds

kobik said:
hi,

how to chose transformer for lvds? all the transformer
i found are for LAN or telecomm.

can i use transformer for Ethernet (i use CAT5)?

thx,
kobik :?:

Hi Kobik,
if you need a fast interface circuit to convert LVSD input signal to standard CMOS, I can provide a circuit topology based on 3 bjt you can easily check on spice.

:roll: t-linux
 

Wenye

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ethernet transformer spice model

kobik said:
hi,

how to chose transformer for lvds? all the transformer
i found are for LAN or telecomm.

can i use transformer for Ethernet (i use CAT5)?

thx,
kobik :?:

I don't know why you want to employ a transformer in LVDS signal path. You want to isolate from two different gnd plane or two different device?

If so, you can used a 1:1 RF transformer with high bandwidth.

Pls check this link for mini-circuit: www.minicircuits.com
 

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