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Propagation Delay Delta tolerance value in mils

GK MN

Hello

 

I usually set relative propagation delay  delta tolerance value in mils like “0:100mils” . One of the board I received for modification having it set in “ns” and the max length difference is 311mils , but still its shows green.

 

Just wanted to know “0.01ns means how much in mils ? ( I consider 140ps = 1000mils  , but this doesn’t match with the constraint set in CMGR)

 

I referred below two document  to get the value , but unable to correlate with CMGR value .

 

Document ref : https://www.flowcad.ch/cms/upload/ApplicationNotes/FlowCAD_AN_PCB_Constraining_Delay_Rules.pdf

 

Document ref : https://www.eetimes.com/meeting-timing-specs-on-boards-with-picoseconds-of-margin/

  • steve

    You also have a pin delay value set (actual component pin to bond die) which is being taken into account. The calculation is being made based on propagation velocity factor (In CM Analyze - Analysis Modes - Electrical). 

  • GK MN
    in reply to steve

    Thanks Steve , You figure it out rightly. I missed the pin delay set in CMGR. Thanks once again

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