See

 

It was donated by @ericgibbs .

Hi @Ian0
Please link me to that donated part, if it is incorrect it should be updated.
E

 

Hi @Ian0
Please link me to that donated part, if it is incorrect it should be updated.
E

when I originally tried it, and just made SPICE do an I/V plot, it looked exactly as I would have expected. The “ideality factor” is a depth of knowledge of SPICE that doesn’t interest me that much, although probably it should!

 

hi,
Checking the LTS standard.dio, this is what I see for a number of Zener diodes.
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.model D1N746 D(IS=1E-11 RS=13.65 N=1.27 TT=5E-8 CJO=5.826E-10 VJ=0.75 M=0.33 BV=3.1 IBV=0.01 Vpk=3.3 mfg=Motorola type=zener)
.MODEL D1N747 D(IS=1E-11 RS=12.8 N=1.27 TT=5E-8 CJO=5.422E-10 VJ=0.75 M=0.33 BV=3.344 IBV=0.01 Vpk=3.6 mfg=Motorola type=zener)
.MODEL GP3V9 D(IS=1E-11 RS=11.84 N=1.27 TT=5E-8 CJO=5.076E-10 VJ=0.75 M=0.33 BV=3.77 IBV=0.01 Vpk=3.9 mfg=Motorola type=zener)
.MODEL GP4V3 D(IS=1E-11 RS=11.84 N=1.27 TT=5E-8 CJO=5.076E-10 VJ=0.75 M=0.33 BV=4.182 IBV=0.01 Vpk=4.3 mfg=Motorola type=zener)
.MODEL GP5V0 D(IS=1E-11 RS=7.708 N=1.27 TT=5E-8 CJO=4.068E-10 VJ=0.75 M=0.33 BV=4.946 IBV=0.01 Vpk=5.0 mfg=Motorola type=zener 500mW)
.MODEL GP5V1 D(IS=1E-11 RS=7.708 N=1.27 TT=5E-8 CJO=4.068E-10 VJ=0.75 M=0.33 BV=5.05 IBV=0.01 Vpk=5.1 mfg=Motorola type=zener 500mW)
.MODEL GP9V1 D(IS=1E-11 RS=5.672 N=1.27 TT=5E-8 CJO=2.523E-10 VJ=0.75

Also checking through @eetech00 lib post

MODEL MD3 D IS=2.5e-12 N=2.20732 XTI=0 EG=0.1
D2 5 4 MD2
.MODEL MD2 D IS=2.5e-12 N=6.92105 XTI=0 EG=0.1
EV1 1 5 6 0 1

 

hi @Ian0
This maybe a better source of info for Zener modelling.
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https://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/spice-models/

 

I guess you guys need to work that out. GIGO!

hi @Papabravo

The value I posted for @Ian0 was Is=1E -11 value, taken from the LTS standard.dio

This sub cct text, is clipped from the posted AAC link, it shows Is=2.75E-11 for this particular Zener
So I don't follow your dismissal of that value I posted.?

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.SUBCKT DI-1N4744A 1 2
* Terminals A K
D1 1 2 DF
DZ 3 1 DR
VZ 2 3 13.7
.MODEL DF D ( IS=27.5p RS=0.620 N=1.10
+ CJO=78.3p VJ=1.00 M=0.330 TT=50.1n )
.MODEL DR D ( IS=5.49f RS=0.804 N=1.77 )
.END

 

I was wondering how to model a solar panel without having to join up all the series diodes.

You can simulate a string of diodes by adding n= xx (where xx is the number of diodes) to the end of the diode type parameter, like this:

The voltage at A above is ~7.3V

 

hi @Ian0,
This is another Solar Cell option.
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Does “.Parma n=36” mean that there are 36 diodes in series?

 

hi,
This is the asc file for that plot, experiment with the settings.
The 12V source on the Vout is a 12V simulated battery load, delete if not required.
[Note the Is=1n]

I have done some sims for 12V battery charging from this circuit, if you are interested,ask.
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hi @Papabravo

The value I posted for @Ian0 was Is=1E -11 value, taken from the LTS standard.dio

This sub cct text, is clipped from the posted AAC link, it shows Is=2.75E-11 for this particular Zener
So I don't follow your dismissal of that value I posted.?

E

.SUBCKT DI-1N4744A 1 2
* Terminals A K
D1 1 2 DF
DZ 3 1 DR
VZ 2 3 13.7
.MODEL DF D ( IS=27.5p RS=0.620 N=1.10
+ CJO=78.3p VJ=1.00 M=0.330 TT=50.1n )
.MODEL DR D ( IS=5.49f RS=0.804 N=1.77 )
.END

I don't think you followed what I wrote very carefully. It was taken from the schematic posted by @Ian0 from the .param statement on that schematic. He then used the value of parameter Is from that parameter statement in a calculation for lower case n which was then used for the diode model "dpv".

See the .param statement on the schematic in post #27 where the expression n=Vmax*38.6/log(Imax/Is) is used. AFAIK that particular definition has nothing to do with any other model except the "dpv" model. If you evaluate that expression using the defined parameters you get what appears to be a ridiculous value. As we have already noticed the letter "N" has overloaded meanings for a diode depending on the scope. Inside the model card is different than outside the model card.

 

He then used the value of parameter Is from that parameter statement in a calculation for lower case n which was then used for the diode model "dpv".

The .param statement came with the model.

 

Hi Papa,
From Post #33 it 'appeared' that I had posted an inaccurate value for Is=1E-11, when typically the default value for that parameter when used with a LTS Zener model is : Is= 1E-11

BTW: I do read your posts carefully, but as they say, 'if in doubt, ask', so I did...

E

 

The .param statement came with the model.

Well that's a weak defense. I cannot fathom what the original model intended to do. It makes no sense for either of the intended purposes of the parameter n as "number of diodes" or the ideality factor of a single diode unless I'm really missing something.

 

Hi Papa,
From Post #33 it 'appeared' that I had posted an inaccurate value for Is=1E-11, when typically the default value for that parameter when used with a LTS Zener model is : Is= 1E-11

BTW: I do read your posts carefully, but as they say, 'if in doubt, ask', so I did...

E

I was never questioning any use of Is as an actual parameter on an actual diode. I questioned the use of the label Is, defined as a parameter outside of any diode model to compute an expression for "n" which was then plugged back into the model for "dpv".

 

Also checking through @eetech00 lib post

What lib post? I didn't post any lib.

 

hi eetech,
Woops sorry about that.
I will go outside and beat myself with a wet tree branch.
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hi eetech,
Woops sorry about that.
I will go outside and beat myself with a wet tree branch.
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Be careful with the self-flagellation. We wouldn't want to lose you.

 

Well that's a weak defense.

It’s the best defence I’ve got. I‘ll add to that “it seemed to work”! Do I need more than two flimsy excuses?
When it produced a valid looking I/V curve, I didn‘t examine it any closer.

 

It’s the best defence I’ve got. I‘ll add to that “it seemed to work”! Do I need more than two flimsy excuses?
When it produced a valid looking I/V curve, I didn‘t examine it any closer.

You get a pass for treading into terra incognita without a good map.