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Lanzones

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Posts: 3
Gold Coast, Australia

digital isolation using Pulse transformer
Sep 06^th, 2006, 7:30pm

I would like to design a isolation transformer that have 0.5mm physical separation between
areas of windings. This is to comply design to astringent mining safety certification. This will work much more like a digital isolator with
LVDS signal @100MHz as an input. load current will be around ~3.3V/25ohms and the DC offset is around 1.5~2V. Could you help me decide on the right ferrite core and specify what type best way to goaround this even the selection of the wire sizes.
I have tried seen icoupler from analog devices and the ISO from texas instrument but the separation between isolation is <<0.5mm. I ahve also tried using ehternet transformer with 10/100Mbps application but the separation between the primary winding and sencondary have no official document.

Hope you could help me with this... Thanks

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loose-electron

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Posts: 1638
San Diego California

Re: digital isolation using Pulse transformer
Reply #1 - Sep 7^th, 2006, 8:54am

Have you looked into developing a model for this using Sonnet or another electromagnetic model tool? You can at least get a the EM properties there and put an approximate model into a time domain simulator.

Also, a minor comment - sending digital signals with lots of harmonic content through a transformer results in some "interesting" phase responses, that tear apart the digital characteristics of the input signal.

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Jerry Twomey
www.effectiveelectrons.com
Read My Electronic Design Column Here
Contract IC-PCB-System Design - Analog, Mixed Signal, RF & Medical

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Lanzones New Member Offline Posts: 3 Gold Coast, Australia	Re: digital isolation using Pulse transformer Reply #2 - Sep 7^th, 2006, 2:56pm could you suggest a magnetic sim tool that I can use? I would be glad to know the materials they use for 10/100Mbps ethernet isolation transformer. Thanks...
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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: digital isolation using Pulse transformer Reply #3 - Sep 7^th, 2006, 11:31pm Sonnet if you are willing to pay the price. ASITIC if you want a freebie (google it, it is available as a UC Berkley download.) There are others from AWR, AnSoft and others. The results you get there constitute a model, that then needs to be put into a SPICE type simulation tool.
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Lanzones New Member Offline Posts: 3 Gold Coast, Australia	Re: digital isolation using Pulse transformer Reply #4 - Sep 8^th, 2006, 3:35am Thanks LE... this forum is great... hope you could give me more view on my next post...
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