can anyone explain how scan works?

[liletian]

Hi All

Can anyone explain how scan work in digital design?

I mean even I have a scan control signal in all design flip-flop. How can I use it for test purpose?

I assume there will have a scan input signal, then based on this input signal, you can verify a chain to see if it is functional. am I right?

Even so, you can not debug your problem to a specific flip-flop, how would that help?

Do I miss something here?

Also, in the design, there normally has a few scan chain, how can you determine how many scan chain that you need?

Thanks

 

[layowblue]

Search for wiki for this general question, and you will get much clearer