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Datasheet - To - Device Model??

Discussion in 'Electronic Basics' started by Randy Gross, Nov 24, 2004.

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  1. Randy Gross

    Randy Gross Guest

    Greetings,

    In the last few days, I've had a lot of success in creating device
    models for the CM6 spice program, providing I could find and enter the
    data in the appropriate fields.

    My question is this: can a devices modeling parameters be "manually"
    gathered solely from its' datasheet or, would extraction software be
    the only means? If so, could you direct me to an area of study?

    These are devices I have datasheets for but no discernable spice data
    yet:

    TPDV640 Alternistor
    DB4 Diac
    BTB06-600T Triac

    1.5K E68CA Bidirectional Diode (no datasheet as of yet)

    Randy
     
  2. Depends on how detailed the data sheet is, and how accurate you want the
    model, but in general, yes you can make a good enough model from a data
    sheet.

    You need to understand the basic characteristics of the devices. So have
    a look at description of the devices you want to model.
    You want to have a go at modifying existing models of the same type. If
    CM dont have them, there are some example diacs and trics in that other
    Spice program:)


    Kevin Aylward

    http://www.anasoft.co.uk
    SuperSpice, a very affordable Mixed-Mode
    Windows Simulator with Schematic Capture,
    Waveform Display, FFT's and Filter Design.
     
  3. Depending on realism required, yes, a comprehensive datasheet should
    in theory give you enough to substitute parameters in an existing
    model or subcircuit of CM.
    None of my books (including AoE) gave me a definition of
    'alternistor'. After 10 mins googling all I've been able to establish
    is that it seems to be a triac that doesn't operate in quadrant IV. If
    there are other distinctions, maybe someone can enlighten me please?
    I'd have thought that was relatively easy to make as a CM macro, with
    two back to back (suitably specified) diodes. Or even just *use* two
    diodes in the circuit.
    My approach would be substitution into one of CM's 54 triacs, after
    examination of the data sheet. That said, I recall giving up on a
    similar exercise a year or so ago, with a MOSFET I think, largely
    because I couldn't find several of the specific CM parameters listed
    explicitly in any manufacturer's data sheet. I suspect that will be
    the problem with a triac too. Taking a look at the first of those 54,
    the MAC15A6 I see this:

    *400V 15A pkg:TO-220 2,3,1
    ..SUBCKT XMAC15A6 1 2 3
    QN1 5 4 3 NOUT OFF
    QN2 11 6 7 NOUT OFF
    QP1 6 11 3 POUT OFF
    QP2 4 5 7 POUT OFF
    DF 4 5 DZ OFF
    DR 6 11 DZ OFF
    RF 4 6 40MEG
    RT2 1 7 18.8M
    RH 7 6 87.5
    RGP 8 3 23.1
    RG 2 8 11.5
    RS 8 4 102
    DN 9 2 DIN OFF
    RN 9 3 41.6
    GNN 6 7 9 3 15.2M
    GNP 4 5 9 3 18.1M
    DP 2 10 DIP OFF
    RP 10 3 29.5
    GP 7 6 10 3 10.3M
    ..MODEL DIN D (IS=45.8F)
    ..MODEL DIP D (IS=45.8F N=1.2)
    ..MODEL DZ D (IS=45.8F N=1.5 IBV=10U BV=400)
    ..MODEL POUT PNP (IS=45.8F BF=5 CJE=4.02N TF=38.2U)
    ..MODEL NOUT NPN (IS=45.8F BF=20 CJE=4.02N CJC=804P TF=2.55U)
    ..ENDS XMAC15A6

    Maybe one of the professionals here can step you through how you would
    change that 400V 15A TO-220 to your BTB06-600T?
    I think they behave like diacs with greater power capability.
     
  4. Bi-directional Diode - A plain piece of wire.

    Kevin Aylward

    http://www.anasoft.co.uk
    SuperSpice, a very affordable Mixed-Mode
    Windows Simulator with Schematic Capture,
    Waveform Display, FFT's and Filter Design.
     
  5. Diacs are 'stateful' devices, like SCRs or TRIACs. When their avalanche
    voltage is reached, they 'break over', and exhibit negative resistance.
    They are often used to trigger triacs for this reason.

    Diodes won't do this.

    CM doesn't have a diac model, but here is a site that has some models:

    http://users.skynet.be/hugocoolens/spice/power/

    I haven't tried them out in CM yet.

    --
    Regards,
    Robert Monsen

    "Your Highness, I have no need of this hypothesis."
    - Pierre Laplace (1749-1827), to Napoleon,
    on why his works on celestial mechanics make no mention of God.
     
  6. Randy Gross

    Randy Gross Guest

    Thanks again for the direction,

    I found this info on the Alternistor:

    "A special chip offers the same performance as two thyristors
    (SCRs) wired inverse parallel (back-to-back), providing better
    turn-off behavior than a standard triac. An alternistor may be
    triggered
    from a blocking to conduction state for either polarity of
    applied AC voltage with operating modes in Quadrants I, II,
    and III.
    This new chip construction provides two electrically separate
    SCR structures, providing enhanced dv/dt characteristics while
    retaining the advantages of a single-chip device."

    This may be a key to modeling this device: "electrically seperate
    SCRs", "wired inverse parallel" provided I can trigger them. The
    circuit that contains these components is located at:
    www.twelvemileroad.com/welder_control.html and is unusual indeed.

    The bi-directional diode gave me pause too. If wired as configured in
    the circuit, nothing will pass through, a complete "open". There has
    to be more to it but, I can't find it.

    Randy
     
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