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Thread: IR2110 Buck Converter HO dead time

  1. #1
    New Member New Member jsaalva is on a distinguished road
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    IR2110 Buck Converter HO dead time

    Hi

    I am working on a synchronized buck converter using the integrated IR2110 as driver for the mosfet, I see that when the output capacitor (C1) is connected dead time on the HO pin there is 12V, but I have not yet identified the reason for because this happens

    Attached is a capture of the simplified circuit diagram, and the signals taken at different points:

    Yellow: IR2110 HIN
    Blue: IR2110 LIN
    Violet: IR2110 HO (marked in orange dead time)
    Green: IR2110 VS

    Duty cylce: 50%
    Dead time: 2 uS


    Can you help me identify the reason?
    Thanks


    Click image for larger version

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    Click image for larger version

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    Last edited by jsaalva; Dec 29th, 2018 at 03:06 AM.

  2. #2
    New Member New Member
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    wchu1 is on a distinguished road
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    Hi Jsaalva:
    The operation of the driver looks fine.
    Please use the differential mode voltage probe to check the waveform between HO and VS. The reference of high side Mosfet (Q1) is VS, not COM.

    Regards
    Weidong Chu
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

  3. #3
    New Member New Member jsaalva is on a distinguished road
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    Hi Weidong Chu,

    I agree with what you are saying, with respect to VS are zero volts (which is correct), however, my doubt is that without the output capacitor (C1), the HO voltage during dead time is zero volts with respect to COM (not vs), but with C1 is 12V respect COM, that's my doubt


    Thanks

  4. #4
    New Member New Member
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    Hi Jsaalva:

    I guess this is because there isn't enough energy which stored in the buck inductor (when the high side Mosfet is on) to charge the output capacitor (when the high side Mosfet is off).

    That means the buck converter works in discontinuous mode. You may use the current probe to check the inductor current to see the difference between with and without the output capacitor.

    Regards
    Weidong Chu
    The views expressed here are my personal opinions, have not been reviewed or authorized by Infineon and do not necessarily represent the views of Infineon.

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