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Thread: I need a help about SG3525

  1. #11
    Quote Originally Posted by dinithm View Post
    I made SMPS for a car amplifier,
    but there is un expectable spike on it

    this is the waveform at IDLE
    Attachment 4500
    1A load
    Attachment 4501
    heavy loads (<3A output)
    Attachment 4502
    this is data of my transformer
    Attachment 4503

    Attachment 4504Attachment 4505

    can u pleas tell me ,what is the reason of that matter.and what do I do to resettle this ,
    thank you.
    Is it working swiftly now.......!

  2. #12
    diysmps Member*
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    no its not working

  3. #13
    diysmps Member
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    Try to eliminate gap in the transformer core as much as you can.

  4. #14
    diysmps Member*
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    Can you post your actual schematic?

    I am seeing the MOSFET take a very long time to switch, about 1.5 usec
    I would guess problems with the driver, looks like turn ON time is too slow, or way too much deadtime.

    Your transformer calc. tool shows 2usec deadtime on 70kHz PWM which I think is too much.
    Why 21AWG secondary winding for 4A? Seems a bit thin.

    SG3525 can have troubles driving big mosfets, especially if you have no filter between Vc and V.

  5. #15
    diysmps Member*
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    I bought (T45-26-15 PC40) from aliexpress

    but I didnt compliet the circuit yet


    http://www.aliexpress.com/item/fast-...7-8d4356ee39aa

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