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SD21x spice model?

Discussion in 'Electronic Design' started by Klaus Bahner, Jun 30, 2006.

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  1. Klaus Bahner

    Klaus Bahner Guest

    Hi,

    Does anyone have spice models for the SD210/SD214 DMOS Fets?
    I've found the models from Linear Systems, but they produce clearly
    wrong results at least when used in OrCAD PSPICE. There doesn't seem to
    be anything wrong with the syntax, hence I tend to believe there is
    something wrong with the model parameters. I've contacted Linear Systems
    a while ago, but of course no answer ...

    Regards,
    Klaus
     

  2. Hello Klaus,

    Every Spice model is an approximation for typical parameters of a device.
    What's not correctly simulated?

    Best regards,
    Helmut
     
  3. Klaus Bahner wrote...
    You should be checking with Vishay (was Siliconix).

    My Intusoft spice has models for sd210 through sd215.
    Without looking at them all, I see the capacitance varies
    between types, which is not supported by the datasheets.

    ..MODEL SD210DE NMOS Level=1 CBD=4.65P CBS=5.58P CGBO=20.6N
    + CGDO=2N CGSO=2.4N GAMMA=.992 IS=3.25E-13 KP=7.15M
    + LAMBDA=22.5M MJ=.46 PB=.8 PHI=.75 RD=12 RS=15 VTO=1.15

    ..MODEL SD215DE NMOS Level=1 CBD=8.08P CBS=9.7P CGBO=20.6N
    + CGDO=2N CGSO=2.4N GAMMA=.992 IS=3.25E-13 KP=7.2M
    + LAMBDA=22.5M MJ=.46 PB=.8 PHI=.75 RD=11 RS=13 VTO=1.1

    I have not evaluated these models. In my experience,
    if you want to use a MOSFET model for linear work,
    you have to first vet it against bench measurements,
    and be prepared to make substantial changes.
     
  4. Klaus Bahner

    Klaus Bahner Guest

    Well, it's not just an approximation thing. Even applying 20V as
    gate-source voltage, doesn't switch the Fet completely on. In this case
    the model just creates a drain current of about 600uA (@Vds ~13V)
    corresponding to an on resistance in the order of 20k, although it
    should be only 45 Ohms max.

    Wouldn't call this just the usual difference between modelled and real
    circuit :)


    Cheers,
    Klaus
     
  5. Jim Thompson

    Jim Thompson Guest

    From where can I download the models?

    ...Jim Thompson
     
  6. Klaus Bahner

    Klaus Bahner Guest

  7. Jim Thompson

    Jim Thompson Guest

    I duplicated your result.

    L=0.5u W=889u is NOT a large device.

    What/where are the specs/data-sheet for the real device?

    I note that the library specifies VGSmax = +2.5V

    ...Jim Thompson
     
  8. Hello Klaus,

    You have to specify the size W and L depending on what FET you want.
    Then you will get for the SD210DE about Id=11.9mA @ Vgs=2.5V, Vds=5V.
    The Rds_on is only 10 Ohm with Vgs=10V, but the model is
    only specified for Vgs up to 2.5V.

    Best regards,
    Helmut



    ***** MODEL NAMES: *****
    ***** SD210DE: DMOS device model W=889um L=0.5um T=27C. *****
    ***** BIAS RANGE: VDSmax=20V VGSmax=2.5V VBSmax=-2V *****
    ***** *****
    ***** SD214DE: DMOS device model W=889um L=0.5um T=27C. *****
    ***** BIAS RANGE: VDSmax=12V VGSmax=2.5V VBSmax=-2V *****
    ***** *****
    ***** SD5400: DMOS device model W=889um L=0.5um T=27C. *****
    ***** BIAS RANGE: VDSmax=20V VGSmax=3.5V VBSmax=-2V *****
    ***** *****
    ***** SD5400CY: DMOS device model W=889um L=0.5um T=27C. *****
    ***** BIAS RANGE: VDSmax=12V VGSmax=3.5V VBSmax=-2V *****
    ***** *****
    ***** SST211: DMOS device model W=889um L=0.5um T=27C. *****
    ***** BIAS RANGE: VDSmax=30V VGSmax=2.5V VBSmax=-2V *****
    ***** *****
    ***** SST213: DMOS device model W=889um L=0.5um T=27C. *****
    ***** BIAS RANGE: VDSmax=10V VGSmax=3.5V VBSmax=-2V *****
    ***** *****
    ***** SST215: DMOS device model W=889um L=0.5um T=27C. *****
    ***** BIAS RANGE: VDSmax=20V VGSmax=3.5V VBSmax=-2V *****
    ***** *****
     
  9. Jim Thompson

    Jim Thompson Guest

    OK, I found the problem. The bare model is not SIZED.

    You need to create a part such that its template is...

    MN1 %d %g %s %b SD210 L=0.5u W=889u <<<<

    I then get ID = 12mA at VGS = +2.5V, VDS = +2V

    And the slope near the origin is 52.6 ohms.

    ...Jim Thompson
     
  10. Jim Thompson

    Jim Thompson Guest

    Those models are Level = 1, which suck the big lemon.

    Fortunately Klaus cites models that use PSpice Level = 7, same as
    HSpice Level = 49, and don't require the "Win-fix" ;-)

    ...Jim Thompson
     
  11. Hello Jim,

    The model given by Win has given a "correct" Rds_on of about
    40 Ohms for Vgs=10V. So this model is much better suited for
    switched applications than the model from Linear Systems.

    Best regards,
    Helmut
     
  12. Klaus Bahner

    Klaus Bahner Guest

    Thanks Jim and Helmut,

    I will try that. (Hope I can figure out how to make the necessary
    changes in OrCAD's model editor ...)

    Klaus
     
  13. Jim Thompson

    Jim Thompson Guest

    I haven't seen the data sheet, but the library says VGSmax = +2.5V,
    NOT +10V. I simulated at VGS = +2.5V, thus my slightly higher
    predicted slope.

    As for a Level = 1 model being "better suited" than a Level = 7,
    ROTFLMAO ;-) Even Win admits the Level = 1 model needs a patch.

    Saying a Level = 1 model is "better suited", is like saying a Model-T
    can outrun my Q45 ;-)

    ...Jim Thompson
     
  14. Klaus Bahner

    Klaus Bahner Guest

    I did this already, but couldn't find any models on Vishay/Siliconix' site.
    By the way, it seems as if Linear Systems has acquired the DMOS line
    from Vishay/Siliconix. Although Vishay still lists these devices on
    their homepage, they seem not to make them any longer (Haven't yet got
    an authorative answer from my distributor, though). Then there is a
    company called Calogic, which also offers them, but it could be that
    these devices will be harder to get.

    Are there any alternatives out there, i.e. other small signal, high
    speed, low leakage, lateral MOSFETs without gate protection diodes?

    Klaus
     
  15. Klaus Bahner

    Klaus Bahner Guest


    The datasheet says VGSmax +/- 40V! Hence, in general the 2.5V of the
    model seem to be a limitation, although in my case it's fine, since I
    anyway want to use the smallest possible gate voltage swing to minimize
    charge injection.

    Klaus
     
  16. Joerg

    Joerg Guest

    Hello Jim,
    That's usually when I trudge over to the lab and fire one up. In analog
    apps that include fast switching the "not so known" effects of
    surrounding pulse transformers and stuff like that are hard to simulate.

    Put that 1100HP engine in there plus some Formula-1 rear tires and it
    might just do that ;-)
     
  17. Joerg

    Joerg Guest

    Hello Klaus,
    Don't know what you want to do with them but check out TV tuner FETs
    such as the BF998. Many of the do have diodes but the capacitances and low.

    SD stuff has become harder to buy and some of it like my favorite SD5400
    arrays have become expensive so I am not using them anymore.
     
  18. Jim Thompson

    Jim Thompson Guest

    The machine shop operator was very cordial and bought the engine back.
    Duane had been one of his best customers and had paid for the engine
    even though he knew he was near death.

    ...Jim Thompson
     
  19. Joerg

    Joerg Guest

    Hello Jim,
    That was very nice of him. If they don't part out the engine maybe they
    could let you know where it went so you could see it in action.
     
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