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What's the proper DDR4 termination method in Intel FPGA?

SYiwe
Novice
381 Views

My design contains a DDR4(discrete component) EMIF, and I terminate the address/command/clk in the same way with Arria10 development kit DDR4 daughter card(DIMM). Here're my questions:

  1. The address/command/clk should be pull-up to VTT after the last DDR4 SDRAM, what's the value of VTT? 1.2V or 0.6V? VTT in daughter card is 1.2V(VDD), but in some other example designs VTT=0.6V(VDD/2).
  2. In daughter card, a resistor connects between CK0_T and CK0_C, but no resistor used to pull up CK0_T and CK0_C to VTT, should I add pull-up resistor for CK0_T and CK0_C?

Thanks, regards.

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3 Replies
NurAida_A_Intel
Employee
273 Views

Hi SYiwe,

 

Thank you for joining this Intel Community.

 

Please refer to my answer below:

  1. The address/command/clk should be pull-up to VTT after the last DDR4 SDRAM, what's the value of VTT? 1.2V or 0.6V? VTT in daughter card is 1.2V(VDD), but in some other example designs VTT=0.6V(VDD/2).

[Ans]: Terminate the DDR4 address, command, and control signals to VTT= 0.6V (VDD/2).

 

2. In daughter card, a resistor connects between CK0_T and CK0_C, but no resistor used to pull up CK0_T and CK0_C to VTT, should I add pull-up resistor for CK0_T and CK0_C?

[Ans]: No, no need to add resistor pull-up to VTT.

 

Hope this helps.

 

Thanks

 

Regards,

Aida

 

SYiwe
Novice
273 Views

 Thank you for your answer. But I still have some doubts.

 CK0_T/CK0_C is differential clock output from FPGA to drive DDR4, not the reference clock input to FPGA.

 According to the following figure in user guide, CK0_T/CK0_C should be pull-up to VTT. 

DDR4 termination.PNG

 So I would like to confirm the following conclusion with you: there's no need to add pull-up resistor for CK0_T/CK0_C, is that correct?

 Thanks, regards.

NurAida_A_Intel
Employee
273 Views

Hi SYiwe,

 

Thank you for the diagram and sorry for the confusion. My bad, I was not referring to FPGA output clock at first.

 

Yes, the CK0_T/CK0_C should be terminate pull-up to VTT. You need to follow the terminationguidline based on the I/O standard you used.

 

Regards,

Aida

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