Article ID: 000086843 Content Type: Troubleshooting Last Reviewed: 05/17/2019

Why does the synchronizer chain "altera_std_synchronizer_nocut" have unsafe MTBF in the metastability report in Timing Analyzer?

Environment

  • Intel® Quartus® Prime Pro Edition
  • BUILT IN - ARTICLE INTRO SECOND COMPONENT
    Description

    Due to a problem with the Intel® Quartus® Prime Pro edition version 19.1, the synchronizer chain "altera_std_synchronizer_nocut" might  have an unsafe Mean Time between Failure (MTBF) when it follows an asynchronous transfer. This is because the synchronizer chain is merged with retimer-created registers, which breaks the synchronizer requirements. Without a synchronizer, an asynchronous transfer will have a very low MTBF and be reported as being unsafe.

    Resolution

    To work around this problem for the Intel® Quartus® Prime Pro Edition software, turn off the early retimer by writting the following assignment in the Quartus Settings file (.qsf):

    "set_global_assignment -name FITTER_EARLY_RETIMING OFF" 

    This problem is scheduled to be fixed in a future Intel® Quartus® Prime Pro Edition software release. 

     

    Related Products

    This article applies to 1 products

    Intel® Stratix® 10 FPGAs and SoC FPGAs

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