Little clarity please? IGBT?

Discussion in 'General Electronics Chat' started by Tonyr1084, Feb 14, 2017.

  1. Tonyr1084

    Thread Starter Well-Known Member

    Sep 24, 2015
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    I have this device. An Insulated Gate B ? ? ? T ? ? ? Insulated gate field effect transistor. What's the B all about?

    I know what it is but I don't understand the IGBT, the BT part of it in particular. GP7NC60HD.jpg
     
  2. mcgyvr

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  3. mtonge

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    From Wikipedia:
    An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily used as an electronic switch which, as it was developed, came to combine high efficiency and fast switching.

    Sounds interesting, I'll have to read on to see if it is something I can use too.
     
  4. bertus

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    Apr 5, 2008
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    Hello,

    The IGBT is an insulated gate bipolar transistor.
    The attached PDF's will tell you more.

    Bertus
     
  5. ian field

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    Its basically a hybrid Szicklai pair - a regular MOSFET has an emitter follower strapped to its drain.
     
  6. Tonyr1084

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    So is it more like a B(ipolar)J(unction)T(transistor) or a FET? I recognize the gate is insulated, so it can't be a BJT, there's no "Junction" between the Base & Emitter. Or collector for that fact.

    It comes off a dead garage door opener. I believe it powered the motor. Relays set the motor direction. Up to 160 VDC. I've been scrapping parts off the board. I have seven relays, single pole double throw type. Not sure of the coil voltage though. I suppose I'll get around to googling it eventually.
     
  7. Tonyr1084

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    Sounds greek to me.
     
  8. bertus

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    Tonyr1084 likes this.
  9. Tonyr1084

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    "In essence, the IGFET controls the base current of a BJT, which handles the main load current between collector and emitter. This way, there is extremely high current gain (since the insulated gate of the IGFET draws practically no current from the control circuitry), but the collector-to-emitter voltage drop during full conduction is as low as that of an ordinary BJT." Quoted from Bertus' posting.

    Thanks. That absolutely clears it up. Now I understand the nature of "Hybrid of a MOSFET and a BJT."
     
  10. ian field

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    Its both - 2 devices on one die. A MOSFET and a bipolar transistor connected together.
     
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  11. Tonyr1084

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    Yes, Ian, thanks. Came to that conclusion.

    Thanks all who clarified this for me.

    HEY ALL - RUN OUT AND GET SOME BULK CHOCOLATE AND SOME STRAWBERRIES AND HAVE IT READY FOR THIS EVENING. MELT THE CHOCOLATE IN A SMALL CROCK POT AND DIP THE STRAWBERRIES IN THE CHOCOLATE. USE BABMOO SKEWERS OR ROUND TOOTHPICKS TO HOLD THE STRAWBERRIES.
     
  12. GopherT

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    think of it as a Darlington where the input is a MOSFET gate (high impedance voltage controlled) and the output is a BJT (actually better for very high currents than MOSFET).
     
  13. MaxHeadRoom

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    Here is more from IR.
    Max.
     
  14. ian field

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    Its not a Darlington - its different - that's why it has a different name; The Szicklai pair, in this case a hybrid Szicklai pair with a MOSFET and a BJT.

    The Darlington is 2 DC coupled common emitter stages - the IGBT is a common source MOSFET driving an emitter follower BJT.
     
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  15. ian field

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    Not necessarily - The output stage BJT can't saturate, so the on time losses aren't *ALL THAT* less than the RDSon of the older MOSFETs it was developed to replace.

    There have been big advances in reducing RDSon in modern MOSFETs, so the IGBT isn't quite the great wonder it once was. The common emitter output stage also restricts switching speed - for some applications; the IGBT is just too slow.
     
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