how to convert a Pspice model to LTspice

Thread Starter

njk381

Joined Jan 18, 2017
11
Hi all, I'm trying to find a suitable power fet to control a pulsed output. I found this Pspice model and thought I worked out how to convert it to LT spice put evidently I can't. Alternatively does anyone know of a library of nmosfets that can take 1200V at 1.5A?
 

Alec_t

Joined Sep 17, 2013
12,215
Welcome to AAC.
Not sure how useful it would be even if you found/converted the model to LTspice format, since LTspice doesn't account for FET breakdown voltage. Can't you just add a 1200V reverse-biased diode from drain to source of a bog-standard FET model?
 

ericgibbs

Joined Jan 29, 2010
13,670
hi,
LTSpice has a Vds MOSFET with 800v, STW11NM80 Id=11 Amps.
You could open the lib/cmp/standard.mos file, make a copy of the STW11NM80 line of parameters.
Paste that to the end of the standard.mos listing, change the name to say XSTW11NM80, then edit the Vds=800 to Vds=1200.
Then using 'F2' select it.
It should be close enough for trialling

E
 

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Thread Starter

njk381

Joined Jan 18, 2017
11
Hi,
I'm new to using these types of simulation, so I'm wading through the tutorials

here are the specs for that mosfet.
.model STW11NM80 VDMOS(Rg=3 Vto=4.5 Rd=140m Rs=100m Rb=175m Kp=30 Cgdmax=.5n Cgdmin=.05n Cgs=2n Cjo=.3n Is=88p mfg=STMicroelectronics Vds=1200 Ron=350m Qg=44n)

I have assigned the FET to the added script but it isn't performing. Is there another spec I should change? This will at least prove the concept as I know I can purchase the FET I need.
 

eetech00

Joined Jun 8, 2013
2,584
Hi all, I'm trying to find a suitable power fet to control a pulsed output. I found this Pspice model and thought I worked out how to convert it to LT spice put evidently I can't. Alternatively does anyone know of a library of nmosfets that can take 1200V at 1.5A?
Check this site:

http://www.ixys.com/TechnicalSupport/pspice.aspx

They have a number of high VDS mosfets (including 1200v) with pspice models you can use in LTspice without conversion.
 

Thread Starter

njk381

Joined Jan 18, 2017
11
sorted the opto. must of replaced the original.
My next question is how to read the script for the FET model. What do the figures correspond to?
 

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Thread Starter

njk381

Joined Jan 18, 2017
11
Yea that's it thanks, 100us pulse letting through approx 960V every 1.2s

This may sound daft but please bear with me. could you provide a brief explanation of what you've done. When I work out circuits on paper it all seems to work, but sometimes I run a sim and it goes pear shaped.
Like I said its something I'm trying to learn.
 

ericgibbs

Joined Jan 29, 2010
13,670
hi,
Added 150R limiting resistor to the opto emitter, you should always limit the emitter current to the specified value.
Added a 1meg Gate to Source
Opto supply to 12V, note its 0v is referenced to to the MOSFET Source, so it MUST be floating in the actual circuit.

That is it.

I have been using LTS for a long time and I am still learning.
Look at other LTSpice threads on the Forum, there are some interesting/novel circuits.

Ask if you have problems.

E
 

ericgibbs

Joined Jan 29, 2010
13,670
Thanks for all the input. really appreciate it
hi,
Your'e welcome.
With ref to the 1meg , Gate to Source resistor, consider the state of the Gate when the opto transistor is Off, the Gate is open circuit and 'floating'.
So the internal Gate capacitance is still charged from the last On period, the MOSFET will remain conducting.
The 1meg provides a discharge path.
E
 

Bordodynov

Joined May 20, 2015
2,910
Hi.
My model:
.model C2M0025120D_AB vdmos(rg=1.1 vto=2.25 rd=-5m rs=20m rb=6.7m kp=2.6 ksubthres=.1 mtriode=3 theta=20m lambda=40m cgdmin=15p cgdmax=2n cgs=2825p tt=15n ibv=1.5m nbv=20 a=0.7 is=3.6p cjo=2.52n bv=1600 m=0.368 eg=3.26 vj=0.6 n=3.9 vds=1200 ron=25m
 
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