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Contributor
Contributor
4,567 Views
Registered: ‎07-18-2014

Requirement for Differential Clock IOs

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Hi all

In ds182,I only find the issues about about GTX Reference clock,that should be focused on.What should be considered When I use an oscillator to connect the Clock capable IOs?

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Moderator
Moderator
8,687 Views
Registered: ‎07-23-2015

Re: Requirement for Differential Clock IOs

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@chenxuol Not sure if you mean what are the specs of the clock generator you should be looking for to drive Clock capable I/O's. 

 

If so, first it depends on what frequency you planning to use, check what IO standards it can output (generally LVDS is preferred) and check its Jitter values

- Giri
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Xilinx Employee
Xilinx Employee
4,557 Views
Registered: ‎04-16-2012

Re: Requirement for Differential Clock IOs

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Hi @chenxuol

 

See whether clocking resources user guide helps you: https://www.xilinx.com/support/documentation/user_guides/ug472_7Series_Clocking.pdf

Also post your exact query.

 

Thanks,

Vinay

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Xilinx Employee
Xilinx Employee
4,540 Views
Registered: ‎08-01-2008

Re: Requirement for Differential Clock IOs

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you just need to make sure use correct PIN number and use proper clocking constraints . Check this guide
https://www.xilinx.com/support/documentation/sw_manuals/xilinx2016_2/ug903-vivado-using-constraints.pdf
https://www.xilinx.com/video/hardware/creating-basic-clock-constraints.html
Thanks and Regards
Balkrishan
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Moderator
Moderator
8,688 Views
Registered: ‎07-23-2015

Re: Requirement for Differential Clock IOs

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@chenxuol Not sure if you mean what are the specs of the clock generator you should be looking for to drive Clock capable I/O's. 

 

If so, first it depends on what frequency you planning to use, check what IO standards it can output (generally LVDS is preferred) and check its Jitter values

- Giri
--------------------------------------------------------------------------------------------------------------------
There's no such thing as a stupid question. Feel free to ask but do a quick search to make sure it ain't already answered.
Keep conversing, give Kudos and Accept Solution when you get one.
-----------------------------------------------------------------------------------------------------------------------

View solution in original post

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Contributor
Contributor
4,517 Views
Registered: ‎07-18-2014

Re: Requirement for Differential Clock IOs

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Hi,@Moderator

I want to check whether the output voltage of the oscillator can meet Clock capable I/Os.I have found the description in ds182,Table 12: LVDS_25 DC Specifications.

Thanks!

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Moderator
Moderator
4,514 Views
Registered: ‎07-23-2015

Re: Requirement for Differential Clock IOs

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@chenxuol Thanks for the clarification. Since LVDS is not a rail to rail standard, the main conditions that need to be checked are if VOD (Output Differential Voltage) and VOCM (Output Common Mode Voltage) of transmitter (in your case the clock chip) are within limits of VID (Input Differential Voltage) and VICM (Input Common Mode Voltage) of the receiver (in your case Kintex) given in Table 12 as you mentioned.

 

Just FYI, LVDS_25 is for HR banks (2.5V) while LVDS is for HP banks (1.8V). Both have similar specs though. 

- Giri
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There's no such thing as a stupid question. Feel free to ask but do a quick search to make sure it ain't already answered.
Keep conversing, give Kudos and Accept Solution when you get one.
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