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Participant zvs
Participant
628 Views
Registered: ‎04-08-2017

Kintex-7 GTX receivers open ports

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Hi!

 

I'm using the XC7K160T. In the device I've utilized four GTX receivers in the MGT_BANK_115 and one receiver in the MGT_BANK_116. Should I connect the remaining receivers' input pins in the MGT_BANK_116 to ground or should I leave them floating?

 

Thanks in advance!

 

Best Regards, zvs.

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1 Solution

Accepted Solutions
537 Views
Registered: ‎01-22-2015

回复: Kintex-7 GTX receivers open ports

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@zvs

 

     What is the "biased" and what is the "not biased"?

I am not sure, but …   For some RX_CM_SEL settings, FPGA input-pins for the receiver are connected through 50-ohm resistors to a voltage (MGTAVTT or Programmable – see Fig 4-2, UG476) and I suspect this is called “biased”.  

 

Again looking at Fig 4-2, for these “biased” conditions it makes sense to leave input-pins unconnected for an unused receiver.   If you instead ground input-pins of a “biased” and unused receiver, then there could be large and unnecessary current draw through the 50-ohm resistors shown in Fig 4-2.

 

Mark

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5 Replies
604 Views
Registered: ‎09-17-2018

Re: Kintex-7 GTX receivers open ports

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For best ESD protection, unused pins maybe connected to ground,

 

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Xilinx Employee
Xilinx Employee
587 Views
Registered: ‎06-02-2017

回复: Kintex-7 GTX receivers open ports

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Hi zvs,

 

There are details about how to deal with unused MGT pins in the UG476, you can check this doc, Table 5-7 for details.

 

 

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Participant zvs
Participant
562 Views
Registered: ‎04-08-2017

回复: Kintex-7 GTX receivers open ports

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Thanks for the replies!


I've seen the Table 5-7 of the UG476, but I'm confused a little. What is meant when it's said "biased" (If a receiver is not used and not biased, connect the associated pin pair to ground. If the receiver is not used but biased, leave the pin pair unconnected.).
Does it mean powered MGT supply rails, or it means configured RX termination voltage (except the FLOAT option)? What is the "biased" and what is the "not biased"?

 

Best regards, zvs.

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538 Views
Registered: ‎01-22-2015

回复: Kintex-7 GTX receivers open ports

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@zvs

 

     What is the "biased" and what is the "not biased"?

I am not sure, but …   For some RX_CM_SEL settings, FPGA input-pins for the receiver are connected through 50-ohm resistors to a voltage (MGTAVTT or Programmable – see Fig 4-2, UG476) and I suspect this is called “biased”.  

 

Again looking at Fig 4-2, for these “biased” conditions it makes sense to leave input-pins unconnected for an unused receiver.   If you instead ground input-pins of a “biased” and unused receiver, then there could be large and unnecessary current draw through the 50-ohm resistors shown in Fig 4-2.

 

Mark

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Participant zvs
Participant
523 Views
Registered: ‎04-08-2017

回复: Kintex-7 GTX receivers open ports

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Thank you for the reply, Mark! Apparently this is true.

 

Regards, Zvs.

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