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LM3478 based Sepic Converter design validation

Mitali Mistry33
Prodigy 40 points
Other Parts Discussed in Thread: LM3478

Hi,

I want to use LM3478 as sepic converter for following design parameters:

Vinput: 10V - 28V

Vout: 12V

Iout: 1A

I have attached the schematic for  reference.  I have used Appnote AN1484 for equations.

Please let me know anything need to be done for optimization. Anyone who has used LM3478 based sepic converter can share their experience too. 

Regards,

Mitali

  • 0
    TI__Expert 4100 points
    Hi Mitali,
    Without detailed check of your calculations, schematic looks OK.
    One suggestion would be to slightly increase output capacitance value (C725) to 47uF.

    Regards
    Brani
  • 0 in reply to Brani Dubocanin
    Prodigy 40 points
    Hi Brani,

    Thanks for the reply and your suggestion.
    I have calculated following basic parameters as per AN - 1484:

    1. Duty Cycle : 56%
    2. L1=L2=L = 25uH, I have taken coupled inductor so L=15uH is choosen
    3.Peak Currents of Inductors: 1.5A and 1.2A
    4. Peak Mosfet current: 2.7A
    5. Vsense = 130mV (from datasheet graph)

    I will surely go for higher output capacitor value.

    Regards,
    Mitali