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Thus, in this context, you cannot afford to have Latch_FF go metastable even for one clock.
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In my case it should work fine because Latch_FF.Q is guaranteed not to be used until T2. If Latch_FF goes metastable at T1 then it must mean that D will be stable for some 8ns before T2. In other words, Tsu is about 8ns with a multi-cycle path setting of 2.
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Also, metastability is not ensured to last just one clock...
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The following documents say that a metastable condition will resolve itself in roughly tco of the FF.
http://www.altera.com/literature/wp/wp-01082-quartus-ii-metastability.pdf ftp://ftp.altera.com/pub/lit_req/document/an/an042.pdf I have not been able to find tco or internal flip-flops but logic says that it must be much, much less than 8ns.
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The little mistake you had is that, in this type of application, if the -setup multiplier is N, then -hold muliplier is N-1. 2 and 1 in your case.
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Thanks. I will update my SDC.
Honored Contributor
