Electronic Circuits and Projects Forum

Originally Posted by crutschow

Only if the analog circuitry is nonsense.

No, very straightforward designs start showing significant differences with empirical results after you add more than a couple of dozen analog components. Changing the update speed and adding digits to the precision settings doesn't improve it beyond a certain point - and that point is in the dozens, not hundreds, of analog components. If you had any experience with it, you would be painfully familiar with the problem.

Originally Posted by Sceadwian

There is only one limitation to a simulator, the amount of effort spent inputting the boundaries of the simulation as they occur in the real world. It's all about the parasitic components that the user does not input.

Originally Posted by Sceadwian

Again duffy, this isn't a fault of the simulator but of the person that creates the simulation, in order to get true to life simulation you'd have to add every parasitic that exists in a real world circuit

No, there's also "simulation speed" and "precision settings" (among others) that have a greater effect. Anyone who actually works with them on a regular basis, using more than a handful of components, becomes very familiar with the inherent weaknesses of simulators.

Originally Posted by duffy

No, there's also "simulation speed" and "precision settings" (among others) that have a greater effect. Anyone who actually works with them on a regular basis, using more than a handful of components, becomes very familiar with the inherent weaknesses of simulators.

Can you post a .ASC file that illustrates your point?

Originally Posted by duffy

No, very straightforward designs start showing significant differences with empirical results after you add more than a couple of dozen analog components. Changing the update speed and adding digits to the precision settings doesn't improve it beyond a certain point - and that point is in the dozens, not hundreds, of analog components. If you had any experience with it, you would be painfully familiar with the problem.

I've had considerable experience with Spice simulators and have used one to simulate a full buck switching regulator, including the loop response, with good success, for example. What are these "significant differences" and "inherent weaknesses" you are referring to that you are so painfully familiar with?

hi duffy,

If you are aware of any short comings in LTSpice, it would be helpful if you could post examples.

E.

I can dig something up, but you would have to actually build a circuit with - like I said - more than a couple dozen analog components and compare signals between the two. After a certain level of complexity the simulator waveforms just don't match what's on the scope.

crutschow - The analog part of your "buck regulator" reduces to what - a coil, a diode, a drive transistor, couple of caps and a voltage comparator? I've had no problem simulating coil drivers very much like that, and from an analog standpoint, also very simple.