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LM5156-Q1: WEBENCH Power Designer vs LM5155/56 DC/DC Boost Controller Design Tool which one should be used?

David Cheung
Prodigy 120 points
Part Number: LM5156-Q1
Other Parts Discussed in Thread: LM5156EVM-BST, LM5155, LM5156

I need a design using LM5156 in boost CCM or DCM mode for input voltage of 12V to 24V and an output voltage variable between 50V to 200V and a current of 5ma max at 200V. I have tried various ways to get the parameters using the WEBENCH Power Designer online version and the LM5155/56 DC/DC BOOST Controller Design Tool (excel version) and using the same input parameters and frequency the results are drastically different in the compensation component values. Which one should be used? How can I get a stable design using the LM5156 chip? I have the LM5156EVM-BST and my own PC board that I have laid out. I can reproduce the 3.5Vin to 12V 3A output design with the same values as in the evaluation board. But I am not able to get the right component values for our requirement of 24Vin to 200V 5ma output design. I can use either CCM or DCM. 

Please help.

Thanks

  • 0
    TI__Mastermind 47911 points

    Hi David,

    thank you for using the E2E forum.

    Boosting from 12V up to 200V is quite a big conversion ratio. This only can work with DCM when using a Boost design.

    We have an reference design which would fit very well to your requirement - this uses a small charge pump to simplify the boost stage design.

    PMP20183 reference design | TI.com

    Best regards,

     Stefan

  • 0 in reply to Stefan Schauer
    Prodigy 120 points

    I saw the Lidar design with voltage tripler on the spec. But I was hoping I do not need to use that. I can design it for 16V supply and 150V output for 0.1 A load. My question is that I tried both the WEBENCH Power Designer and the LM5155/56 DC/DC BOOST Controller Design Tool (excel version) using the same VIN and VOUT and IOUT and frequency of 440KHz or 291KHZ, the values of RT, RFB, and RCS, the calculated BODE PLOT and RCOMP and CCOMP and CHF are completely different. Which one is correct? Should I use the WEBENCH or the excel values?

  • 0 in reply to David Cheung
    TI__Mastermind 47911 points

    Hi David,

    To my knowledge the Webench Tool has some more restrictions so it will not support native DCM operation.
    So wonder that you could generate a Webench design with this parameters.

    Can you please share your design so that I can check:
    - Click on the 3 dots it the right top corner

    - Share -> public link

    - paste the link here

    Best regards, 

     Stefan

  • 0 in reply to Stefan Schauer
    TI__Mastermind 47911 points

    Hi David,


    I have not seen an update on this thread for the last 14 days.

    If the issue is solved it would be great to press the is solved button.

    If there is still something open, just let me know with the new details.

    Best regards,

     Stefan

  • +1
    Prodigy 120 points

    I was able to use the LM5155/56 DC/DC BOOST Controller Design Tool (excel version) to get a design and it worked. I had to do some fine tuning to get a bode plot good enough for it. So now I have a design of 16Vin to 200V out at 10ma. Thanks.