L
Lostgallifreyan
Guest
Joerg <invalid@invalid.invalid> wrote in
news:7dbmdvF2bkgdrU1@mid.individual.net:
http://www.edn.com/archives/1998/071698/pdf/15di.pdf
completion and complexity. Ignoring the rest for now, I'm focussing on that
EDN one because it looks like it's meant to be complete. But it's NOT in a
single subcircuit file that can be adapted to LTspice, or anything else. I
don't think it needs modelling, just translation.
For modelling, I'll look into that too, as equations are given in that PDF
file I mentioned earlier, from Intusoft. In their descriptions of how to use
SpiceMod (which I learned costs 600 bucks(!) and is therefore the most
expensive few tens of kilobytes I've ever heard of) they show a screen that
neatly prioritises the data sheet specs for pluging into the equations. While
the details for transisotrs (bar a MOSFET) are not similarly revealed, there
ought to be enough there in their diode explanations to model a laser diode,
electrically. But again, all I'm asking for here right now is for someone who
knows how, to translate that EDN article to a subcircuit ready to plug into
LTspice. (I can make my own symbol file).
news:7dbmdvF2bkgdrU1@mid.individual.net:
Sorry, right file, wrong location. Try this:Lostgallifreyan wrote:
Joerg <invalid@invalid.invalid> wrote in
news:7dbdd3F2b0r74U2@mid.individual.net:
Lostgallifreyan wrote:
If anyone is following this and wants to try modelling their own
stuff, I found what might be a way.
Intusoft make a tool called SpiceMod which is part of a package they
call ICAP4 though it seems the demo setup doesn't have that tool,
just some very good noted on it, and modelling in general:
The file WkwModels.pdf from the demo install answers a lot fo the
questions I had about modelling diodes, which parameters to tweak,
and extraction from data sheets.
I don't know if the lack of response to me is because of a thousand
experts silently screming RTFM at me, or because it's actually
asomething they DON'T KNOW. Given that Intusoft explain that this is
a serious challenge for experts too, I'm assuming maybe they really
don't know, so they might benefit from that file as much as I will.
Most of us just use a regular diode to simulate because all one
(usually) wants to know is that there definitely won't be any ever so
slight spike in diode current because LDs can go poof in microseconds.
Simulating the optics part would be a major challenge, I think.
Thought that might provoke an expert.I agree, same here, that's all
I usually need too, though like that EDN manual says, a more detailed
model that allows models to give warning of imminent demise is useful.
Modelling for ESD is likely daft, better that we just take care and put
in TVS's and such, but when it comes to fast modulation, a model
definitely helps. Surely you'd have a use for that, no?
I have designed LD circuitry but I am not an expert. Senor Hobbs would
be one. TVS don't work well. Their cutoff isn't terribly well defined
and they have too much capacitance for this. Just handle the things with
care. I've never killed one with ESD, knock on wood ;-)
While I found that a string of four 1N4148's produced a modelled
overshoot almost exactly like what I saw on an oscilloscope months
before I considered looking at spice, I got a very different result
when trying four 1N4001's so it really does need something better than
reaching for a standard diode, in a model OR as a dummy diode in a real
circuit (where a optically dead laser diode is best anyway). So it
really comes down to trying to get something usefully close! EDN's
model seems ideal, aimed at solving this problem for general use, as
opposed to the elaborate models in private university publications.
EDN's is probably tested too, proofread and verified before publishing.
http://www.e-insite.net/ednmag/archives/1998/071698/pdf/15di.pdf
(Halfway through file).
"File not found" :-(
http://www.edn.com/archives/1998/071698/pdf/15di.pdf
I've been finding (and been sent) spice models that are in various stages ofSome of the 4000 series behave more like PIN diodes.
If anyone can help by making that into asy and sub files for LTspice it
will help me a lot, and probably a lot of other people too. Four days
of searching have found lots of other people askign questions, and very
few answers, and NONE complete and verified. Someone could get well
known for solving this so other people can have an easier time of it.
It's going to be lots of work. You'll need to get into behavioral models
and while people have modeled large chunks of jet engines with that it
was a ton of work.
completion and complexity. Ignoring the rest for now, I'm focussing on that
EDN one because it looks like it's meant to be complete. But it's NOT in a
single subcircuit file that can be adapted to LTspice, or anything else. I
don't think it needs modelling, just translation.
For modelling, I'll look into that too, as equations are given in that PDF
file I mentioned earlier, from Intusoft. In their descriptions of how to use
SpiceMod (which I learned costs 600 bucks(!) and is therefore the most
expensive few tens of kilobytes I've ever heard of) they show a screen that
neatly prioritises the data sheet specs for pluging into the equations. While
the details for transisotrs (bar a MOSFET) are not similarly revealed, there
ought to be enough there in their diode explanations to model a laser diode,
electrically. But again, all I'm asking for here right now is for someone who
knows how, to translate that EDN article to a subcircuit ready to plug into
LTspice. (I can make my own symbol file).