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LM5021: Transformer simulation setting problem while designing SMPS with LM5021

Ashokraj Pilli
Prodigy 210 points
Other Parts Discussed in Thread: LM5021

Hi, 

          I am trying to design AC to DC converter with flyback topology. With input RMS voltage =240V, ouput 24V, 2A. I have used web bench power supply to design this circuit. I have simulated the circuit in TINA but I am not getting desired ouptut. I would like to know the following : 

  1. I would like to know why am I not getting desired output when I have designed the circuit similar to web bench power supply. Is something wrong with Web bench or it is the issue with TINA or my circuit designing? I have used non linear secondary output transformer and editted the total number of windings to suit the requirement. Please let me know what are the changes I will have to make in this circuit to get the desired ouput.  
  2. I have attached my TINA file.

    I suspect the reason for faulty output is due to transformer

    -

Thanks,

Ashok

  1. 7853.WBDesign40.pdf2465.LM5021.TSC
  • 0
    TI__Prodigy 590 points

    Hello Ashok,

    Your thread has been assigned. You should receive a reply within a week.

  • 0 in reply to Pye Naing
    TI__Guru* 85926 points

    Hello Ashok,

    The Webench design should be correct.   Could you double check your Webench design versus your Tina schematic to make sure they are the same?

    Webench generally outputs simulated waveforms showing the design worked.  If those files looked O.K. there is something wrong with your simulation and/or schematic in Tina.

    If your output is not what you expect it could be because the transformer turns ratio and primary magnetizing inductance is not correct.  Another possible issue is that the DC divider is not setup correctly.

    The Tina simulation tool can help you troubleshoot your design.  Look at test points such FET current, CS signal and feedback network to see if the circuit is behaving the way you expect.  This should highlight the issue you are having and should be able to adjust components to get the desired output.

    Regards,