Circuit circus

[JoeJester]

... but I would a high degree of compatibility across simulators.

As such, do you have any comments concerning the second link in post number 1? Is LTSpice within complete agreement with the displayed values on both the original and modified model parameters?

The OP brought that link into the discussion as prima fascia evidence of model problems. This is no slam against any particular Spice program. The pSpice f3 manual does illustrate the default values for each parameter.

 

[ericgibbs]

hi Joe,
I am not out to slam any program, they all have their merits, especially LTSpice which is free.
What I would like see is compatibility in options and parameter names etc, in sub circuit models across simulator programs.

When we post a simulation/circuit, we are constantly reminded that the 'active' component parameters are only typical, we know that already.
Carl posted a valid comment regarding designing circuits that cater for the spread in component values.
E

 

[alec_t]

All bug reports are appreciated and will be resolved

Well I reported a 'bug' with the D-flop model to LT and was politely told it wasn't a bug as far as they were concerned. So it wasn't resolved to my satisfaction . [Run a sim involving a D-flop (eg the basic flop or a CD4013) with both R and S high. According to datasheets both Q and not-Q should go high].

 

[JoeJester]

According to datasheets both Q and not-Q should go high.

Just so I am clear, attached is a clean copy of what I've seen in the TI datasheet covering the SN7474, SN74LS74A, and the SN74S74. You are talking about the conditions where both outputs are high ... which is not guaranteed by the manufacturer.

 

[JoeJester]

Eric,

Cost is usually a big factor in any simulation program. In that aspect, LTSpice has over 2 million users, according to some sources. They didn't specify if that number were downloads or LTSpice usergroup membership or how they came about that number. In that same article, it stated they were the "defacto standard" spice program.

We have National Instruments teaming with Multisim, Texas Instruments teaming with TINA to have a free version on their website called TINA-TI, and there are a host of online simulators in the "free" category.

It always boils down to the needs of the end user. If cost is the driver, FREE is best. I will tell people which simulator I use. I started with EWB back at version 4.x before it was renamed multisim. I switched to TINA a couple of years later, because of the features I wanted were part of that software package.

When we post a simulation/circuit, we are constantly reminded that the 'active' component parameters are only typical, we know that already.

We certainly do know they are whatever the model maker considers typical ... and could be compared against the datasheet and a handful of circuits for accuracy.

What I would like see is compatibility in options and parameter names etc, in sub circuit models across simulator programs.

The parameter names are covered in the pSpice f3 manual. Any program or model claiming to be compatible with pSpice should already be using those parameters. The options list could be quite extensive and some programs already contain easy access with a single click some graphing options. Others require you to pick the variables you want to manipulate for the graph. Some provide capabilities for both. Some allow you to customize the simulation parameters as well as the model parameters. Attached is a partial listing of the parameters I can change.

All internet posted information is "as is." It's up for the reader to decide the correctness of the information. I'm still doubtful about that second link in post 1 of this thread.

 

[vinodquilon]

JoeJester,

I don't know what you mean by replicate. But, does it seem right that the 2N3904 would have a typical beta value (BF) of 416.4 (notice the decimal for this wildly varying parameter)? And, does any transistor have a saturation current (Is) of 6.734 femtoamps? It appears to be a good idea to look at the netlists of any simulator to see what they are using for their models.

Ratch