How to calculate the time to reach steady state using LTSPICE?

[Patrick_66]

Hello everyone, can anyone teach me how to calculate the time required to achieve steady state for a system using LTspice?
The figure is shown below.

Thank you in advance.

 

[dick_freebird]

Generally at electrical test you'd run the pattern in a loop
and walk the strobe back from the final value toward zero
until the output has "broken out" of its "accept mask" (or
simple limit). This works in simulation too.

You need to assert a tolerance or U/L limit pair for a quantity
you can get at. Then develop that quantity (e.g. the pulse
peak or flat-top). Then a rack of measure statements to
grab each (say) flat-top voltage into a vector, along with a
companion time-point vector.

Now index back to front through that "accept" vector with
a break-logic using the limit-pair, and report value and time
at the index.

 

[cupoftea]

Yes thats right, and generally the time LTspice takes depends on your processor speed....as well as the number of time points you may select, and what solver you select, and whether you use .save directives.

 

[Patrick_66]

Generally at electrical test you'd run the pattern in a loop
and walk the strobe back from the final value toward zero
until the output has "broken out" of its "accept mask" (or
simple limit). This works in simulation too.

You need to assert a tolerance or U/L limit pair for a quantity
you can get at. Then develop that quantity (e.g. the pulse
peak or flat-top). Then a rack of measure statements to
grab each (say) flat-top voltage into a vector, along with a
companion time-point vector.

Now index back to front through that "accept" vector with
a break-logic using the limit-pair, and report value and time
at the index.

Hello Sir, do you have any website or videos that teach this?

 

[Patrick_66]

Yes thats right, and generally the time LTspice takes depends on your processor speed....as well as the number of time points you may select, and what solver you select, and whether you use .save directives.

Hello Sir, do you have any website or videos that teach this?

 

[KlausST]

Hi,

Hello everyone, can anyone teach me how to calculate the time required to achieve steady state for a system using LTspice?

You get different answers. This because the question was not clear.

What "time" are you asking for?
* The time for the signal in the diagram to be considered as "stable" by using the timing information of the X-Axis?
* or the processing time the computer needs to find the "stable state" ... in the meaning how long you have to wait in front of your computer ... the time you can measure by using your watch....

Klaus

 

[Patrick_66]

Hi,



You get different answers. This because the question was not clear.

What "time" are you asking for?
* The time for the signal in the diagram to be considered as "stable" by using the timing information of the X-Axis?
* or the processing time the computer needs to find the "stable state" ... in the meaning how long you have to wait in front of your computer ... the time you can measure by using your watch....

Klaus

Sorry for not stating out clearly. I wanted to ask for the time for the signal in the diagram to be considered as "stable" by using the timing information of the X-Axis?

 

[danadakk]

http://web.mit.edu/2.737/www/extra_files/unused%20files/trans.pdf

https://web.engr.oregonstate.edu/~webbky/ENGR202_files/SECTION%204%20Second%20Order%20Transient%20Response.pdf

The above if you want to do it analytically.


Regards, Dana.