Dumb LTSpice question - subckt model

On Tuesday, February 24, 2015 at 10:31:49 AM UTC-5, Phil Hobbs wrote:
> On 2/24/2015 10:22 AM, Jim Thompson wrote:
> > On Mon, 23 Feb 2015 21:44:56 -0800 (PST), dagmargoodboat@yahoo.com
> > wrote:
> >
> >> I've never used a mfr model that was a subckt before; I've always added
> >> the .MODEL to the LTSpice library file, or edited an existing device.
> >>
> >> This Vishay MOSFET has a more complex model though, and she ain't loadin'
> >> Jim.  LTSpice says it can't find the model for M1.
> >>
> >> I even tried putting the definition right in the .asc, still no joy.
> >>
> >> I followed the LTSpice help info, as best I could.  Any obvious goofs?
> >>
> >> Thanks,
> >> James Arthur
> >> --------------
> >> Version 4
> >> SHEET 1 2188 1188
> >> WIRE 752 144 304 144
> > [snip]
> >
> > "TEXT" doesn't read as netlist, just as commentary.
> >
> > You want to add a "Spice directive"...
> >
> > .LIB C:\Path1\Path2\etc\library_filename.lib
> >
> > (Extension doesn't matter, I just tend to use .lib)
> >
> > Put all your models in that file.
> >
> > See "LTspiceTutorials.zip" on the Simulation Tools & Macros Page of my
> > website for lots of helpful hints.
> > 		
> >                                          ...Jim Thompson
> >
> You also have to right-click on the symbol and change the prefix to "X". 
>   Otherwise it's looking for a .model statement.

That was it Phil.  Thanks!

With that change the model works as a .SUBCKT in the .ASC file itself, and also
as a .LIB file with the .LIB command.

James Arthur

Everybody hits that snag at some point. I think it was Joerg who clued me in. 

Cheers

Phil Hobbs

On Tuesday, February 24, 2015 at 11:22:40 PM UTC-5, Jim Thompson wrote:
> On Tue, 24 Feb 2015 20:13:44 -0800 (PST), dagmargoo...@yahoo.com
> wrote:
> 
> >On Tuesday, February 24, 2015 at 10:22:40 AM UTC-5, Jim Thompson wrote:
> >> On Mon, 23 Feb 2015 21:44:56 -0800 (PST), dagmargoo...@yahoo.com
> >> wrote:
> >> 
> >> >I've never used a mfr model that was a subckt before; I've always added
> >> >the .MODEL to the LTSpice library file, or edited an existing device.
> >> >
> >> >This Vishay MOSFET has a more complex model though, and she ain't loadin'
> >> >Jim.  LTSpice says it can't find the model for M1.
> >> >
> >> >I even tried putting the definition right in the .asc, still no joy.
> >> >
> >> >I followed the LTSpice help info, as best I could.  Any obvious goofs?
> >> >
> >> >--------------
> >> >Version 4
> >> >SHEET 1 2188 1188
> >> >WIRE 752 144 304 144
> >> [snip]
> >> 
> >> "TEXT" doesn't read as netlist, just as commentary.
> >> 
> >> You want to add a "Spice directive"...
> >
> >Thanks Jim, but it's in the LTSpice file as a .subckt SPICE directive.
> >
> >> .LIB C:\Path1\Path2\etc\library_filename.lib 
> >> 
> >> (Extension doesn't matter, I just tend to use .lib)
> >> 
> >> Put all your models in that file.
> >
> >I also tried that, using a .LIB statement.  Didn't work. That's why I'm
> >confused--it looks like it couldn't find the file, which was in the same
> >directory as the .ASC file. It still didn't work when I have a full path
> >either.
> >
> >Since I tried the obvious things, I figure I'm missing something simple.
> >Maybe I made a typo or so such.
> >
> >> See "LTspiceTutorials.zip" on the Simulation Tools & Macros Page of my
> >> website for lots of helpful hints.
> >
> >Will do.  Thanks.
> >
> 
> I've been trying to break Mikey of this "same directory" bull-shit...
> to no avail.

Hey, Mike's a star!  LTSpice has done more for the planet than <fill in the
blank>.

I was simulating a Linear Tech dc-dc converter and wanted an easy check on
the FET losses.

It didn't work.  Once I got the model recognized, LTSpice broke to a micro-crawl
flashing "defcon 1" in the status line when I ran the converter in the one mode
I was chasing. (It simulates rapidly and cleanly in 'buck', but 'boost' makes
it panic and freeze-crawl.

Oh well.  I can 'scope it on the hardware. I'd just wanted to explore a few
alternate FETs--these are getting a bit hot for the sealed box these puppies
will be bedding down in.

Thanks Jim,
James Arthur