Frequent failures of HIP4080 MOSFET driver..Give suggestions

Discussion in 'The Projects Forum' started by mehta_manish, Apr 4, 2010.

  1. mehta_manish

    Thread Starter New Member

    Apr 4, 2010
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    .We have made an evaluation board containing 4080 as well as 4081 as MOSFET driver, 'H' bridge using MOSFETs (IRF7230, IR250, IR520.. all from International Rectifier) and LC filter. (L=30 mH, C= 0.1 uF)and resistor as a load. There are two supplies to baord. 12V for 4080ARH and 24V for MOSFETs. The 'ON' sequence is first give 50 Hz sine and 50 KHz triangle waves (square wave in case of 4081) to 4080, power 4080 and then power the MOSFET. Initially, load is kept high around 200 Ohm to limit the current from MOSFET to around 120 mA. At this point, everything works OK. After LC filtering, 50 Hz sine wave is recovered at load resistor end. This works OK upto drain current of around 250 mA. However, whenever drain current is increased to around 400 mA, 4080 or 4081 fails. The failure symoptom is loss of level shifting for higher end MOSFETs i.e. BHO and AHO pins have driving waveform without level shifting (boot-strapping or volatage doubling does not take place). ALso, 4080 and 4081 gets warmer and starts to draw more than 50 mA at 50 KHz switching of PWM. Till now, around 8 ICs (4080 and 4081) have failed with similar failure signature that either at BHO or AHO gate end, level shifting or boot-strapping does not occur. Please, note that, IC works normaly at lower drain current (which is done by putting higher load resistor). However, at higher drain current, it fails. MOSFET does not show any failure or Anomaly. Actual application needs 4A of current from MOSFET. SO, we are worried how to use IC at this higher drain current of MOSFET. We also replaced inductor with resistor to weed out cause of failure due to incuctor. But, still IC fails in same mode. PLEASE, help us.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I suggest that you start by posting your schematic.

    Schematics are a "language" that are much more easily understood than attempting to describe a circuit using words.

    [eta]
    Please post your schematic using the .png format. PNG is compact, requires no additional software to read, and is not "lossy" or fuzzy like .jpg format images are.

    Use the "Go Advanced" and "Manage Attachments" buttons to attach your image to your reply or original post.
     
  3. mehta_manish

    Thread Starter New Member

    Apr 4, 2010
    3
    0
    Dear Sir SgtWookie
    Thank you very much for reply.
    Please, find enclosed schematic in pdf form with value of component. If more info is required, please let me know.
    Regards..
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I've re-formatted your original problem statement, as I found it hard to read without breaking it up into paragraphs:

    The MOSFETs have a large total gate charge of around 120nC, and your bootstrap capacitors (C1, C9, etc) are only 0.1uF. This seems to be rather undersize. How did you arrive at the 0.1uF figure?

    I am also wondering why you are driving the 4080 with sine and triangle waves instead of square waves that vary in duty cycle?

    You will probably need to PWM the high-side MOSFETs, as the boost caps will discharge fairly rapidly. If you try to keep the high-side MOSFETs turned on for very long, the boost caps will discharge, and you will wind up operating the MOSFETs in the linear region.
     
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