signals passing from analog to digital in mixed signal design

[sun_ray]

In a mixed signal design, signals will pass from analog to digital domain and vice-versa. What are the typical guidelines for signals passing from analog to digital?

Regards

 

[morris_mano]

In scan mode, signals from analog to digital should be not toggling and signals from digital to analog should be some safe value.
proper level shifter if voltage domains are different between analog and digital.
If digital can be powered off separately, then proper isolation cells.

 

[sun_ray]

In scan mode, signals from analog to digital should be not toggling and signals from digital to analog should be some safe value.

Why is it necessary?

 

[jbeniston]

Why is it necessary?

So your analog logic doesn't start doing some random function, and in the reverse direction, so help improve test coverage.

 

[sun_ray]

So your analog logic doesn't start doing some random function, and in the reverse direction, so help improve test coverage.

Can you break up your sentences so that the meaning out of your sentences are clear? Random function in which sense? Random function in forward or backward direction?