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hello,
I learned a lot from the "TimeQuest User Guide" edited by Rysc.
But I was confused that the Tco_ext has different expression on page 20 and page 21 as follows:
P20
External device parameters:
Tco_ext = Tsu of external device
minTco_ext = Th of external device
P21
External device parameters:
Tco_ext = Tco of external device
minTco_ext = min Tco of external device
In my opinion, Tco is the delay time from clk to output port Q, we should use this parameter for set_input_delay, but in some chip datasheet,I could not find Tco,such as the datasheet of TFP401, in this way, how can I write the constraint of set_input_delay?
thank you!
Andrew
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You are right but TCO_ext is not = TCO of external device rather it is just another name for it.
The issue you raised is because some chips do not give you TCO but rather tSU/tH required at receiving device and then this translates to:
TCO(max) = UI - tSU
TCO(min) = tH
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