[SI-LIST] Re: CHGND connection in DVI connector
- From: qantrix <qantrix@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Tue, 4 May 2010 17:01:21 +0200
Steve,
you mean direct connection or through caps/resistors?
2010/5/4 steve weir <weirsi@xxxxxxxxxx>:
> Bill I recommend against the the second drawing. Please see the attached.
>
> Best Regards,
>
>
> Steve.
> wjcsongr@xxxxxxxxxxxxxxxxxxx wrote:
>>
>> The second image shows the DVI signals crossing under the split in the
>> ground planes...why wouldn't I be concerned about that Steve?
>>
>> Regards,
>>
>> Bill
>>
>> William Csongradi
>> Senior Electrical Engineer
>> Rockwell Collins Heads Down Display Center
>> 319-295-7884
>>
>> Mailing Address
>> Rockwell Collins
>> 400 Collins Road NE
>> MS 105-167
>> Cedar Rapids, Iowa 52498-0001
>>
>>
>>
>>
>> *qantrix <qantrix@xxxxxxxxx>*
>> Sent by: si-list-bounce@xxxxxxxxxxxxx
>>
>> 05/04/2010 08:15 AM
>>
>>
>> To
>> si-list@xxxxxxxxxxxxx
>> cc
>>
>> Subject
>> [SI-LIST] Re: CHGND connection in DVI connector
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Steve,
>>
>> http://img504.imageshack.us/i/currentdesign.png/
>> you can find current design. data(diff.pairs) shield connected to sgnd.
>>
>> suggested design see here
>> http://img266.imageshack.us/i/suggested.png/
>>
>> As you can see ch_gnd will cover all area of dvi connector and pins of
>> data pairs shield connected to ch_gnd.
>> diff.pairs will pass under separation between planes.
>>
>> Idea make it like this seems like bad.
>>
>> But it's possible to connect pairs shield to ch_gnd without creating
>> slot under pairs and cable will have only quite ch_gnd shield for each
>> pair and not dirty sgnd. Question is - does this shield carrying
>> return currents ? How it will work from EMC point ?
>>
>>
>>
>> 2010/5/4 steve weir <weirsi@xxxxxxxxxx>:
>> > Is there a reason you want to isolate signal common from chassis?
>> > Common
>> > practice is to join the two near the chassis boundary. If you attempt
>> > to
>> > isolate them, you will have lots of capacitive sneak paths. If they are
>> > joined you will not have a CM discontinuity issue.
>> >
>> > Steve.
>> >
>> > qantrix wrote:
>> >>
>> >> I have question about CHGND connection in DVI connector/cable.
>> >> There is two kind of shields - one - is shield for data/clock pair;
>> >> second - whole cable shield.
>> >> http://en.wikipedia.org/wiki/Digital_Visual_Interface
>> >>
>> >> We had some EMC consultation - was suggested to connect internal pairs
>> >> shield to chgnd.
>> >> on pcb make polygone chgnd that cover area up to end of dvi connector.
>> >> So diff.pairs will run under slot of gnd.separation.
>> >>
>> >> Question is - how should be connected internal shields in DVI
>> >> conenctor - to sgnd or to chgnd?
>> >>
>> >> diff. pairs running on the slot - seems like bad idea?
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>> >
>> >
>> > --
>> > Steve Weir
>> > IPBLOX, LLC 150 N. Center St. #211
>> > Reno, NV 89501 www.ipblox.com
>> >
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>
>
> --
> Steve Weir
> IPBLOX, LLC 150 N. Center St. #211
> Reno, NV 89501 www.ipblox.com
>
> (775) 299-4236 Business
> (866) 675-4630 Toll-free
> (707) 780-1951 Fax
>
>
>
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