I have had a little play with this. I had a look at the graphs. They
show an output graph something like the output characteristis of a
transister, but Vce being replaced by the input current. This implies
some sort of limiting. However, into a s/c the current follows the
input with a scale factor, requiring limiting to be removed.
What I have done here, is use an iout=i/(i+K) to form a limiter, but
multiplyed K by the output voltage such that as V goes to zero the
limiting goes away.
The graphs are roughly of the right shape with different loads (1M to
10M to open and under s/c conditions, but I have not tweaked them yet.
Preliminary idea PVI15080N:
*************
.subckt PVI anode cathode out_plus out_neg
*
*copyright kevin aylward,
www.anasoft.co.uk.
*this model can be freely used provide this notice is included
d1 anode sense1 dmod1
vsense sense1 cathode 0
biout out_plus out_neg i = -0.001 * i(vsense)/(1 + 80 * i(vsense) *
v(out_plus, out_neg))
rout out_plus out_neg 5Meg
dout out_neg out_plus dmod2
.MODEL dmod1 d(rs=10 cjo=2p is=100p N=2.5 bv=7)
.MODEL dmod2 d(rs=10 cjo=2p is=100p N=1 bv=30)
.ends PVI
**********
I have ignored the output string of diodes for now. I have only spent
a little while on it, so there may be a better way or more accurate
way. The "80" and "5Meg" need to be twiddled to get the best match.
Kevin Aylward
[email protected]
http://www.anasoft.co.uk
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