Do Designers Do Spice Hopping?

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D from BC

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Jan 14, 2007, 5:51:42 PM1/14/07
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Huhhh..another simulator to learn...
First Microcap...then Circuitmaker 2000..then Electronics Workbench
(and it's as rebirth as Microsim)...then Protel...then some misc
magnetics progs..then Orcad.. :-P

Are designers doing this too...Call it spice hopping?

And now I'm checking out LTSpice and reading the documentation:

Taken from:
http://ltspice.linear.com/software/scad3.pdf
"SwitcherCAD III is designed to be used by three different
types of design engineers: those who know what they're
doing, those who think they know, and those who are sure
they know absolutely nothing about switching regulator
design. The experienced designer needs a "what if" program
that allows him to quickly alter aspects of a circuit to
find an optimum design. The neophyte needs a cookbook
approach that yields a reliable design based on the
simplest of inputs. The "loose cannon" designer needs a
program that will allow him to exercise his free will, but
will be intelligent enough to alert him to fatal design
flaws."

I really like the writing style..
"loose cannon" designer :)

D from BC

Tim Shoppa

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Jan 15, 2007, 5:15:38 AM1/15/07
to
D from BC wrote:
> Huhhh..another simulator to learn...
> First Microcap...then Circuitmaker 2000..then Electronics Workbench
> (and it's as rebirth as Microsim)...then Protel...then some misc
> magnetics progs..then Orcad.. :-P
>
> Are designers doing this too...Call it spice hopping?

For better or worse, this happens a lot.

Probably worse. The reason I have to do it is that a SPICE model for
part X only runs in some commercial SPICE version Y, so if I gotta use
that part in SPICE then I might think I need to use only that version Y
of SPICE.

In real life, 90% of the time the reason they say it only runs in SPICE
version Y is because that's the only place they tried it. Often with
minor syntax changes it will run just as well in my favorite SPICE :-).

That doesn't mean the model is useful in any version of SPICE! Almost
all the models even for jellybean parts are useless outside some really
boring range of parameters where the part is perfectly linear, and you
could do just as well (and a lot Faster and with much better
Understanding) on the back of a napkin.

The place SPICE really is useful at is if you really honestly trust all
the models, and for me there's a pretty long list of discrete parts
where I know exactly where to trust the models. So there is zero reason
to use any of those newfangled integrated circuits!

Tim.

D from BC

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Jan 15, 2007, 6:25:40 AM1/15/07
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On 15 Jan 2007 02:15:38 -0800, "Tim Shoppa" <sho...@trailing-edge.com>
wrote:

That's what happened..Some newfangled IC's caught my attention. So I
got sucked into LTSpice.. ("It's a trap.")
All because I'm just trying to save time....
I'm attempting to dodge the time to learn spice file syntax changes
and also to dodge the time creating macro models or equivalent
circuits using all the basics.
Hopping to another spice program seemed like a short cut.

Sometimes I think the more I use spice... the more I get blind and it
becomes my walking stick :)

Thanks for the feedback..

D from BC

Tim Shoppa

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Jan 15, 2007, 6:51:17 AM1/15/07
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D from BC wrote:
> On 15 Jan 2007 02:15:38 -0800, "Tim Shoppa" <sho...@trailing-edge.com>
> wrote:
>
> >D from BC wrote:
> >> Huhhh..another simulator to learn...
> >> First Microcap...then Circuitmaker 2000..then Electronics Workbench
> >> (and it's as rebirth as Microsim)...then Protel...then some misc
> >> magnetics progs..then Orcad.. :-P
> >>
> >> Are designers doing this too...Call it spice hopping?
> >
> >For better or worse, this happens a lot.
> >
> >Probably worse. The reason I have to do it is that a SPICE model for
> >part X only runs in some commercial SPICE version Y, so if I gotta use
> >that part in SPICE then I might think I need to use only that version Y
> >of SPICE.
> >
> >In real life, 90% of the time the reason they say it only runs in SPICE
> >version Y is because that's the only place they tried it. Often with
> >minor syntax changes it will run just as well in my favorite SPICE :-).
> >
> >That doesn't mean the model is useful in any version of SPICE! Almost
> >all the models even for jellybean parts are useless outside some really
> >boring range of parameters where the part is perfectly linear, and you
> >could do just as well (and a lot Faster and with much better
> >Understanding) on the back of a napkin...

>
> That's what happened..Some newfangled IC's caught my attention. So I
> got sucked into LTSpice.. ("It's a trap.")
> All because I'm just trying to save time....
> I'm attempting to dodge the time to learn spice file syntax changes
> and also to dodge the time creating macro models or equivalent
> circuits using all the basics.
> Hopping to another spice program seemed like a short cut.
>
> Sometimes I think the more I use spice... the more I get blind and it
> becomes my walking stick :)

It's not as bad as it was in the late 80's/early 90's, where
Universities were churning out "EE graduates" who had undergone an
intense 4-year course in how to run a specific VLSI design software
tool and nothing else.

I gotta admit, looking back 20 years it made sense, as that was what
all the big semiconductor houses thought they needed to hire lots of.
But it's more frustrating today than it was 20 years ago.

And I myself have carved a niche by being an expert in some really
super-duper obscure software tools when what I really enjoy is not the
tool but the results, but everyone's convinced that I'm the guy they
have to hire just because I know tool X and have used it to do A, B, C,
and D really well.

Sort-of reminds me of when I took a Chaucer class as an undergraduate,
me a techie/science/engineering dweeb among a whole bunch of literature
majors. When the professor was handing back the big term paper, he was
making complimentary remarks about what he really liked in each
student's work. When I got mine back, the comment was "nice printer!".
(I had typeset it using LaTeX and some macros used extensively for
writing Physical Review papers...)

Tim.

Genome

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Jan 15, 2007, 11:12:00 AM1/15/07
to

"Tim Shoppa" <sho...@trailing-edge.com> wrote in message
news:1168861877....@v45g2000cwv.googlegroups.com...

>
> Sort-of reminds me of when I took a Chaucer class as an undergraduate,
> me a techie/science/engineering dweeb among a whole bunch of literature
> majors. When the professor was handing back the big term paper, he was
> making complimentary remarks about what he really liked in each
> student's work. When I got mine back, the comment was "nice printer!".
> (I had typeset it using LaTeX and some macros used extensively for
> writing Physical Review papers...)
>
> Tim.
>

Didn't Chaucer write about one of the meetings of 'The English Society for
Bestiality' and how they met up in a Pub to drink beers and talk tails?

DNA


Jim Thompson

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Jan 15, 2007, 11:21:37 AM1/15/07
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On Mon, 15 Jan 2007 16:12:00 GMT, "Genome" <mrspam...@yahoo.co.uk>
wrote:

"talk tails" ??? Bwahahahahaha!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
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