1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

ZR431 imported into LTspice not working

Discussion in 'Circuit Simulation & PCB Design' started by Flyback, May 9, 2017.

  1. Flyback

    Flyback Well-Known Member

    Joined:
    Jan 5, 2007
    Messages:
    2,009
    Likes:
    34
    Hello,
    Please can you tell why the ZR431 simulation in LTspice is not working?
    Its attached.
    I downloaded the the SUBCKT statement for ZR431 from the diodes.com website.
    The symbol FOR zr431 i made myself...i numbered the pins of the symbol as in the SUBCKT statement.
    I control-right-clicked the symbol and made "prefix" equal to "X" which i beleive is correct procedure.
    Do you know why the sim doesnt run?
     

    Attached Files:

  2. MikeMl

    MikeMl Well-Known Member Most Helpful Member

    Joined:
    Mar 17, 2009
    Messages:
    11,125
    Likes:
    564
    Location:
    AZ 86334
    You didn't have the complete .model
    Your pin order was screwed up.
    I made you a symbol that works.
    .Tran analysis is not appropriate.

    ZR431.png
     

    Attached Files:

    Last edited: May 9, 2017
    • Like Like x 1
  3. Flyback

    Flyback Well-Known Member

    Joined:
    Jan 5, 2007
    Messages:
    2,009
    Likes:
    34
    Thankyou very much. What you sent is brilliant MikeMI. Working well.
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. Flyback

    Flyback Well-Known Member

    Joined:
    Jan 5, 2007
    Messages:
    2,009
    Likes:
    34

    The one thing, in this circuit, the ZR431 is drawing more bias current than its data sheet says it would......the PNP in this simualtion is driven on.
    Do you know why the ZR431 bias current is higher than the datasheet 50uA?

    ZR431 Datasheet
    https://www.diodes.com/assets/Datasheets/ZR431.pdf
     

    Attached Files:

  6. alec_t

    alec_t Well-Known Member Most Helpful Member

    Joined:
    Jul 10, 2011
    Messages:
    9,315
    Likes:
    1,230
    Location:
    Cardiff, Wales
    What do you mean by 'bias' current'?
    The datasheet gives the max ref input current as 1uA, the largest min cathode current for regulation as 50uA, but does not mention 'bias' current.
     
    • Like Like x 1
  7. MikeMl

    MikeMl Well-Known Member Most Helpful Member

    Joined:
    Mar 17, 2009
    Messages:
    11,125
    Likes:
    564
    Location:
    AZ 86334
    Try the attached. Plot V(G). I have encountered this issue with std. TI TL431s. Why should diodes, Inc be any different? Also the model you posted is pretty bad.
     

    Attached Files:

    Last edited: May 10, 2017
    • Like Like x 1
  8. Flyback

    Flyback Well-Known Member

    Joined:
    Jan 5, 2007
    Messages:
    2,009
    Likes:
    34
    Thanks Alec_t, by bias current i mean the bias power to activate the opamp etc inside the zr431.
    Thanks MikeMI ,i will just adjust the circuit so that the 120uA of bias current doesnt mean the PNP in our circuit getting driven on. (ie i will adjust the relevant resistor).
     

Share This Page