TCO reported for wide data widths in M20K blocks with registered outputs in Stratix V devices may be pessimistic

Description

TCO values reported by the TimeQuest Timing Analyzer for Stratix V M20K blocks that use more than 16 bits and that have registered outputs may be pessimistic.

TCO values of output register bits 16 to 39 reported by TimeQuest can be pessimistic by as much as 500 ps. TCO values for bits 0 to 15 are reported correctly.

Resolution

For up-to-date information about Stratix V timing model issues found in the Quartus II software version 12.1, refer to solution number rd11162012_922 in the Altera Knowledge Base.