Problem with IR2117 High side gate driver

Discussion in 'Power Electronics' started by hunterage2000, Oct 1, 2016.

  1. hunterage2000

    Thread Starter Active Member

    May 2, 2010
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    0
    Hi,

    I have simulated the attached circuit without anything connected to HO output. I have a 5V square wave going into IN and a 10V square wave coming out of HO.

    Now I have set the same circuit up on a breadboard and done the same thing but I have a 20V constant voltage coming out of HO.

    Not sure why this is the case. Does anyone know what could be the problem here?
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    What is the value of the capacitor betwen the Vs and Vb ?
    The datasheet shows a 0.1 μF.
    Also what is the value of Vcc?
    What is the value of Vs?
    Vb will be about Vs+Vcc.

    Bertus
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    bertus likes this.
  4. hunterage2000

    Thread Starter Active Member

    May 2, 2010
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    1. The value is 4.7uF electrolytic between Vb and Vs. Didn't see a value of 100nF on the datasheet.
    2. VCC is 20V
    3. VS was about 20V
    4. VB was 19.9V (0.1V drop from diode)
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The bootstrap capacitor is also sized to the frequency of the PWM.
    See link.
    Max.
     
  6. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Don't most mosfet driver App notes say not to use electrolytic caps for that?
     
  7. MaxHeadRoom

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    Jul 18, 2013
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  8. ronv

    AAC Fanatic!

    Nov 12, 2008
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    If you are trying to run the IC by itself you need something from Vs to ground or HO won't go to ground.
     
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