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[SOLVED] scan chain clock waveform

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r1caw ex ua6bqg

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Hi all! I am a student, and now I am study digital design in my university.
Could you, please, explain me the difference between clock waveform during the scan test mode and normal mode? I mean duty cycle difference:

normal mode:
Code:
[I]create_clock -period 100 -name clk -waveform {0 50};[/I]
scan test mode:
Code:
[I]set_dtf_signal -view existing_dft -type ScanClock -port clk -timing {45 50};[/I]
So, why we should use different waveforms?

Thank you very much!
 

Hi all! I am a student, and now I am study digital design in my university.
Could you, please, explain me the difference between clock waveform during the scan test mode and normal mode? I mean duty cycle difference:

normal mode:
Code:
[I]create_clock -period 100 -name clk -waveform {0 50};[/I]
scan test mode:
Code:
[I]set_dtf_signal -view existing_dft -type ScanClock -port clk -timing {45 50};[/I]
So, why we should use different waveforms?

Thank you very much!

Not sure. Where did you get this from?
 

Hi, thank you for your answer!
Actually, I saw it on our example script from teacher during presentation and also in some posts on this forum.
So, the question is why duty cycle can be different?....
 

Hi, thank you for your answer!
Actually, I saw it on our example script from teacher during presentation and also in some posts on this forum.
So, the question is why duty cycle can be different?....

Test doesn't have to run at the same frequency of functionality, so the clock period can be different. The duty cycle shouldn't matter unless you are doing something funky to stress the flip-flops.
 
Thank you!
I understand information about clock frequency? but for duty cycle - I saw it in many scripts in the internet and thats why I was confused.
Can you, please, give me more information about "stress the flip-flop"? Is it related with STA or power?
Thank you in advance.
 

Can you, please, give me more information about "stress the flip-flop"? Is it related with STA or power?

More likely something to do with checking minimum pulse width operation for whatever reason. As this would "stress" the flip-flop with worst case pulse width seen in actual operation.
 
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