Hi,
The rise time is a measure of the scopes speed and can be used to calculate the time it takes for the trace to move from one position to the next, unless of course you intend to use a drive that does not take into account what the rise time actually is. Knowing the rise time allows us to predict and force the trace to go from one place to the next. The equation is:
v2=Vs*(1-e^(-t/RC))
and solving for RC as we measure the time from 10 percent to 90 percent we get a number very close to:
RC=t/2.2
Knowing this means we can calculate the time it takes for the trace to get say vertically with a drive of Vs volts. If that's not fast enough, then we can increase Vs. Let me show one example.
First solve for t:
t=-ln(1-v2/Vs)*RC
If Vs=1v and and v2=0.9 and RC=1 (just for an example) we have:
t=2.3 seconds.
Now make Vs=2v and v2=0.9 and RC=1, and we have:
t=0.598
This should illustrate how knowing the time constant helps us figure out how to get from one place to another in a given time, or how to calculate that time given the other parameters.
Settling time only comes into play when you are forced to work with a voltage that can not be changed on the fly. If that is the case however then you're stuck with that, but you dont have to accept that if you are willing to improve the design
The rise time is a measure of the scopes speed and can be used to calculate the time it takes for the trace to move from one position to the next, unless of course you intend to use a drive that does not take into account what the rise time actually is. Knowing the rise time allows us to predict and force the trace to go from one place to the next. The equation is:
v2=Vs*(1-e^(-t/RC))
and solving for RC as we measure the time from 10 percent to 90 percent we get a number very close to:
RC=t/2.2
Knowing this means we can calculate the time it takes for the trace to get say vertically with a drive of Vs volts. If that's not fast enough, then we can increase Vs. Let me show one example.
First solve for t:
t=-ln(1-v2/Vs)*RC
If Vs=1v and and v2=0.9 and RC=1 (just for an example) we have:
t=2.3 seconds.
Now make Vs=2v and v2=0.9 and RC=1, and we have:
t=0.598
This should illustrate how knowing the time constant helps us figure out how to get from one place to another in a given time, or how to calculate that time given the other parameters.
Settling time only comes into play when you are forced to work with a voltage that can not be changed on the fly. If that is the case however then you're stuck with that, but you dont have to accept that if you are willing to improve the design