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AR# 64774

MIG UltraScale DDR4 - SETUP/HOLD violations in the mmcm_clkout0 domain

Description

Version Found: MIG UltraScale v7.0
Version Resolved: See (Xilinx Answer 58435)

SETUP/HOLD violations might be seen on the following paths (or similar paths) for MIG UltraScale DDR4 designs:

Slack -0.069ns
Source u_sdram1/u_ddr4_ctrl/inst/u_ddr4_mem_intfc/u_mig_ddr4_phy/inst/u_ddr_mc_cal/u_ddr_mc_pi/u_ddr_mc_write/wrQ_reg[1][0]/C   (rising edge-triggered cell FDRE clocked by mmcm_clkout0_1  {rise@0.000ns fall@2.500ns period=5.000ns})
Destination u_sdram1/u_ddr4_ctrl/inst/u_ddr4_mem_intfc/u_mig_ddr4_phy/inst/u_ddr_mc_cal/u_ddr_cal/u_ddr_cal_addr_decode/cal_DQ_reg[421]/D   (rising edge-triggered cell FDRE clocked by mmcm_clkout0_1  {rise@0.000ns fall@2.500ns period=5.000ns})
Path Group mmcm_clkout0_1
Path Type Setup (Max at Slow Process Corner)
Requirement 5.000ns (mmcm_clkout0_1 rise@5.000ns - mmcm_clkout0_1 rise@0.000ns)
Data Path Delay 4.816ns (logic 0.593ns (12.313%)  route 4.223ns (87.687%))
Logic Levels 4  (LUT3=3 LUT6=1)
Clock Path Skew -0.257ns
Clock Uncertainty 0.057ns
Clock Net Delay (Source) 3.212ns (routing 1.417ns, distribution 1.795ns)
Clock Net Delay (Destination) 2.845ns (routing 1.304ns, distribution 1.541ns)
 
Slack (Hold) -0.324ns
Source u_sdram0/u_ddr4_ctrl/inst/u_ddr4_mem_intfc/u_mig_ddr4_phy/inst/u_ddr_mc_cal/u_ddr_cal/u_ddr_cal_addr_decode/cal_RAS_A_reg[4]/C   (rising edge-triggered cell FDSE clocked by riu_clk  {rise@0.000ns fall@5.000ns period=10.000ns})
Destination u_sdram0/u_ddr4_ctrl/inst/u_ddr4_mem_intfc/u_mig_ddr4_phy/inst/u_ddr_mc_cal/u_ddr_cal/u_ddr_cal_addr_decode/cal_RAS_pre_reg[4]/D   (rising edge-triggered cell FDSE clocked by mmcm_clkout0  {rise@0.000ns fall@2.500ns period=5.000ns})
Path Group mmcm_clkout0
Path Type Hold (Min at Slow Process Corner)
Requirement 0.000ns (mmcm_clkout0 rise@0.000ns - riu_clk rise@0.000ns)
Data Path Delay 0.665ns (logic 0.161ns (24.211%)  route 0.504ns (75.789%))
Logic Levels 1  (LUT3=1)
Clock Path Skew 0.825ns
Clock Uncertainty 0.057ns
Clock Net Delay (Source) 1.690ns (routing 0.326ns, distribution 1.364ns)
Clock Net Delay (Destination) 2.467ns (routing 0.836ns, distribution 1.631ns)

Solution

To work around this issue, try using a different implementation strategy, other than "Performance Explore".

If the user logic is being driven by the mmcm_clk domain, try inserting an additional BUFG for the user logic to allow Vivado to properly balance the user and MIG domain. 

If these violations are still seen please open a Service Request for assistance:


http://www.xilinx.com/support/service-portal.html


Revision History:
06/30/2015 - Initial Release
07/06/2015 - Updated solution

Linked Answer Records

Master Answer Records

AR# 64774
Date Created 06/10/2015
Last Updated 07/07/2015
Status Active
Type Known Issues
Devices
  • Kintex UltraScale
  • Virtex UltraScale
IP
  • MIG UltraScale