gate drive circuit

Discussion in 'The Projects Forum' started by harpal, May 12, 2008.

  1. harpal

    Thread Starter New Member

    May 12, 2008
    3
    0
    hi

    i need to design a high speed gate drive circuit with an optocoupler and IGBT...is there any website or circuit that i can look at to give me an idea on how to design it...thanks in advance
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    What is your definition of "high speed"? Do you have a switching rate in mind?

    hgmjr
     
  3. harpal

    Thread Starter New Member

    May 12, 2008
    3
    0
    hi,

    at the moment there is no switching rate specified
     
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Can you at least estimate the upper limit of the switching rate you need to support?

    hgmjr
     
  5. harpal

    Thread Starter New Member

    May 12, 2008
    3
    0
    all rite...lets assume switching rate is at 80kHz
     
  6. Marie

    Member

    Nov 20, 2007
    24
    0
    Hi,

    try to look for 6N137. It works well with MOSFET; i don't know for IGBT
     
  7. ametso

    Member

    Apr 30, 2008
    13
    0
    The 6N137 opto isolator probably don't work with IGBTs.
    Because the 6N137 is designed for digital isolation (low current+voltage ratings). Instead the IGBTs drives a high power and even they have a "FET" like gate (=high input impedance) driving of them requires quit a lot of energy due to the construction of IGBT.

    I check the data sheet of the 6N137 and there found that the absMAX output current is 50mA. So it means that you can't shut down the IGBT very fast (needed some serial resistance between IGBT gate and the opto) keeping gate current under the limit of optos.

    Also you propably can't fully open the IGBT due to the absMAX output voltage limit, whitch was as low as 7V.

    I recommend that you visit some sites of the IGBT manufacturer and explore their application notes about IGBT driving.

    some links for you:
    www.pwrx.com
    www.ixys.com
    www.irf.com
     
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