Are there no MOSFET SCRs?

Discussion in 'General Electronics Chat' started by hp1729, Jan 7, 2017.

  1. hp1729

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    SCR MOSFETs c.PNG SCR MOSFETs b.PNG SCR MOSFETs a.PNG

    Why are there no SCRs with a ground input trigger or MOSFET SCRs?
    Is a negative voltage SCR half of a TRIAC? Never made separately?
     
  2. ronv

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  3. marcf

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  4. hp1729

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    Is that a bad thing?
    An SCR with the input resistance of a MOSFET? Sounds good.
     
  5. hp1729

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    Is that a bad thing?
    An SCR with the input resistance of a MOSFET? Sounds good.
    \Link doesn't work. "RC5 not supported", or something like that. I have TLS enabled.

    (edited to add ...)

    ibiblio is difficult to navigate. Is that SCR thing under "projects". Searching is not intuitive.
     
    Last edited: Jan 8, 2017
  6. GopherT

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    Just get a "sensitive gate" scr. Much lower trigger and hold currents.
     
  7. hp1729

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    How about a ground input SCR instead of a positive voltage trigger? Does anybody make one?
     
  8. ronv

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    I think the body diodes get in the way with the ones you have shown. Always on with a negative supply voltage.
     
  9. GopherT

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    Here

    image.png
     
  10. hp1729

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    Diodes go in the desired direction. On N channel devices the cathode goes toward the Drain. On P channel devices the cathode goes toward the Source.

    Design 1022 e.PNG Design 1022 d.PNG
    I will have to include them. Thanks.
     
    Last edited: Jan 9, 2017
  11. GopherT

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    And since scr and thyristors are commonly used with AC circuits, the body diode screws things up on the negative cycle.
     
  12. shortbus

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  13. RichardO

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    I suspect that IGBT's are winning out over SCR's and triacs. Dealing with the commutation issue can be a b****.

    The same thing happened with bubble memory and CCD memory when dynamic RAM came in.
     
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  14. shortbus

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    Aren't IGBT's just a BJT with a capacitve gate instead of a base? And they still have the intrinsic diode issue.
     
  15. GopherT

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    It is more like a darlington where the input side is a MOSFET and the output side is a BJT. ill have to draw it out when I have a minute to see if the body diode is an issue in the igbt.
     
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