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Re: [Help-gnucap] diode models

From: al davis
Subject: Re: [Help-gnucap] diode models
Date: Sat, 23 Jul 2016 03:42:09 -0400

On Fri, 22 Jul 2016 17:07:51 -0500
John Griessen <address@hidden> wrote:
> and gnucap says, "non-recoverable convergence failure, reducing (itl4)
> newtime=3.300000e-05  rejectedtime=3.300000e-05
> oldtime=3.300000e-05  using=3.300000e-05 tried everything, still
> doesn't work, giving up"

What version of gnucap are you using?

In older versions, there used to be a bug that sometimes messed up time
stepping, causing duplicate time steps, rejecting a step that was
actually good and repeating exactly the same time. It had something to
do with floating point truncation.  I thought it was fixed a few years

If it's a recent version, I want to see your circuit.

On Fri, 22 Jul 2016 17:07:51 -0500
John Griessen <address@hidden> wrote:
> .model 1N4007 D(IS=7.02767n RS=0.0341512 N=1.80803 EG=1.05743 XTI=5
> BV=1000 IBV=5e-08 CJO=1e-11 VJ=0.7 M=0.5 FC=0.5 TT=1e-07 mfg=OnSemi
> type=silicon)

Some of the parameters here are proprietary extensions in some versions
of Spice.

As you figured out ..  Forward voltage drop of a diode is determined
mainly by the parameters IS, N, and RS.  If you are fitting it
expermentally, and have two data points, choose IS to match the
forward voltage at a low current (where the diode exponential is more
pure), then RS to match at a high current (where ohmic resistance

As Felix said, the "native" diode model doesn't implement breakdown.
There are several alternatives available as plugins in
These models are what they are, which may be better or worse than the
"native" "modelgen" model.

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