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Visitor liquan456885
Visitor
6,534 Views
Registered: ‎06-27-2013

K7 GTX CDR setting

   we want to used the recommended CDR setting which advised by UG476 , however, based on the REFCLK PPM parameter, I do not know which I could choose. Could anybody told me how can I get the REFCLK PPM parameter? by the way, I used a 150MHz with 50PPM OSC for the external GTX reference clock source.Thanks.

2013-11-21_151138.png
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7 Replies
Community Manager
Community Manager
6,529 Views
Registered: ‎07-23-2012

Re: K7 GTX CDR setting

REFCLK PPM value is given in the datasheet of the oscillator that you use to supply the GTRELCLKs.

Since, the PPM spec of your oscillator is +/- 50 PPM, you can use the CDR setting given for +/- 200 PPM.

Regards,
Krishna
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Visitor liquan456885
Visitor
6,505 Views
Registered: ‎06-27-2013

Re: K7 GTX CDR setting

      thanks for you kind help,Krishna. Is there any detail introduction for the 72 bit RXCDR_CFG? Thanks.

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Community Manager
Community Manager
6,499 Views
Registered: ‎07-23-2012

Re: K7 GTX CDR setting

No, we don't have the bit description of RXCDR_CFG. User is intended to use values provided in the user guide.

Regards,
Krishna
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Observer prakashdrj
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1,093 Views
Registered: ‎07-12-2016

Re: K7 GTX CDR setting

@smarell,

 

I am using custom protocol which has 0 to 5000 ppm downspreaded and +/-300 ppm of clock, How can I set RXCDR_CFG?

 

Regards,

Prakash

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Moderator
Moderator
1,087 Views
Registered: ‎02-16-2010

Re: K7 GTX CDR setting

If you check the kintex-7 data sheet - DS182, table 62. 5000ppm of down spread with 33khz modulation frequency is supported. If the SSC is outside this spec, the CDR is not characterized for this use case.
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Observer prakashdrj
Observer
1,082 Views
Registered: ‎07-12-2016

Re: K7 GTX CDR setting

@venkata,

 

Agreed, it shown there. But if you can see UG476 not listed parameters for SSC having profile -5000 ppm? Isn't it?

 

How can we configure RXCDR_CFG for that?

 

Regards,

Prakash

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Moderator
Moderator
1,058 Views
Registered: ‎02-16-2010

Re: K7 GTX CDR setting

Please check AR#53364
http://www.xilinx.com/support/answers/53364.html
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