spice simulator recommendation and questions about spice - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: April 06, 2012, 08:35:12 pm
content: I'm thinking of purchasing a circuit simulator and I have a few questions:1)which one do you recommend2)Is spice a generic language i.e as long as it's written in spice any spice capable simulator would be able to read it? Or does it have to be the spice simulator from the component manufacturer?For example right now I'm trying to simulate the lt3080 reg in dave's psu design just as learning exercise. However I've found multisim doesn't have the lt3080 in it's db. At least not the evalulation copy.I was recommended multisim by a electronics student who works at the eletronics store I get my bits from

author: Neilm
author_rank: Super Contributor
timestamp: April 06, 2012, 08:53:15 pm
content: Have you tried some of the free ones that are out there? I have used LTSpice which is a free to download. Dave has used it a couple of times. It is skewed towards AD as they produce it, but if you find a spice model of a part (download from the manufacturer, find on the net etc) you can add it to the model quite easily - it is a text statement.Spice is a reasonably generic language - but there are a few "flavours" of spice out there. LTSpice does have some very useful guides to spice that you can find. I have one at work that explains in detail how the Spice language works. It does also explain about the limitations of the Spice simulation that can trip up the unwary. Each simulation can be done as a simple text file - LTSpice, Tina-TI and the others simply provide a nice front end and an easy way of understanding it.Neil

author: IanB
author_rank: Super Contributor
timestamp: April 06, 2012, 09:31:34 pm
content: In addition to being free, LTspice has a complete library of LT parts.

author: free_electron
author_rank: Super Contributor
timestamp: April 06, 2012, 10:21:35 pm
content: Quote from: amateur_25 on April 06, 2012, 08:35:12 pmtalk about a fuming pile of 'bovine byproduct' ...Get LT spice from Linear Technology. Free , large library of parts. Easy to use ,works really well.Texas instruments also has one : TINA :http://www.ti.com/tool/tina-ti&DCMP=hpa_amp_general&HQS=Other+OT+tina-tiIf you want to shell out some money : Beige Baghttp://www.beigebag.com/is a really good Spice engineBeyond that prices get very large, very quickly.Of course , real men use soldering irons...

author: Bored@Work
author_rank: Super Contributor
timestamp: April 06, 2012, 11:20:07 pm
content: Quote from: amateur_25 on April 06, 2012, 08:35:12 pmStart with the free ones.QuoteLTSpice. Not just because it is free, but it is the only one that should have a model for the LT3080 you mention below. And that model can't be used in any other SPICE, because it is encrypted, and possibly uses proprietary internal elements, too. Which brings us to the next pointQuoteSPICE is relatively generic, but all SPICE manufacturers have added their own extensions. Often, but not always, other SPICE manufacturers copied the extensions of the most popular SPICE versions.In case of Linear Technology's LTSpice they have that propritary encryption extension (they even have two encryption extensions, but that is another issue). Use an encrypted model and you have no chance of portability.QuoteSee above. That model is only available encrypted for LTSpice. Most models from Linear Technology are encrypted, their OpAmps being the exception.QuoteNot if you want to use a Linear Technology part.LTSpice is not the greatest SPICE ever made. It has some annoying things, and a lot of features are badly documented. But you have no alternative.

author: Rufus
author_rank: Super Contributor
timestamp: April 07, 2012, 12:31:56 am
content: Quote from: BoredAtWork on April 06, 2012, 11:20:07 pmAre you sure it is just encryption? I see LTSpice using multiple processor cores with some simulations. Maybe it is just circuit dependant but I got the feeling some of their models were compiled or semi-compiled and/or use non-spice simulator extensions.

author: Bored@Work
author_rank: Super Contributor
timestamp: April 07, 2012, 01:09:12 am
content: Quote from: Rufus on April 07, 2012, 12:31:56 amI never tried to hack it, so on information and believe I say it is at least encryption and proprietary SPICE elements. Some of the proprietary SPICE elements used by their models came to light over the years. What else there might be inside the encrypted model data? Your guess is as good as mine. LTSpice is now multi-threaded and has a matrix compiler. But they did use encrypted models before this was added to LTSpice.

author: IanB
author_rank: Super Contributor
timestamp: April 07, 2012, 01:27:11 am
content: Quote from: Rufus on April 07, 2012, 12:31:56 amIt's not the models that do that, it's the simulation engine. One of the differentiating features of LTspice is a specially optimized computation engine that is claimed to run faster and more efficiently. This may well include making use of multiple cores when they are available.