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LM5163H-Q1: WCCA

Li Zhao
Prodigy 10 points
Part Number: LM5163H-Q1
Other Parts Discussed in Thread: LM5163

Tool/software:

Hello guys

I am using lm5163H-Q1 to build buck converter, now my customer let us to perform worst case analysis, does there is any tools to do it in fast way?

thanks

  • 0
    TI__Mastermind 40040 points

    hello Liz,

    Worst case analysis for what, efficiency?  temp rise?

    David.

  • 0 in reply to David Baba
    Prodigy 10 points

    Hello David,

    Actually, mainly concern voltage/current, such as Input filter ripple current/voltage, output ripple current/voltage....

    I expect 'Quickstart Calculator' only can be used to analysis under normal mode, no worst case analysis.

    For Webech, I am not know if it is reliable for WCCA

    For LM5163 pspice, if it can be used to analys WCCA?

    Li

  • 0 in reply to Li Zhao
    TI__Mastermind 40040 points

    Hello Li,

    PSPICE does not take into account WCA.

    There is no need to compute WCA, the suggestions in the calculator incorporate margins for error. 

    for example, we suggest ripple voltage of ~20mV or so, our ripple can work with voltages much less than this.

    Please follow the guidance provided in the calculator spreadsheet.

    Thanks.

    David.

  • 0 in reply to David Baba
    Prodigy 10 points

    Hello David,

    It means that your calculator already incorporated error? How much error was incorporated in calculator? 10%?

    Let us take one example for 'input capacitor' nominal value 20uF, which capacitance is changing with temp., freq....., then we will get a capacitance range such as 18 - 22uF.

    At the moment, if we wand to get WCA for 'input voltage ripple', do we need to put 18uF and 22uF to get deviation, or we only input 20uF then we will get a ripple voltage which already consider 10% tolerance?

    Thanks

    David

  • 0 in reply to Li Zhao
    TI__Mastermind 40040 points

    No Li,

    You have to derate the COUT capacitors yourself.  When we determine the amount of ripple voltage, there is margin in it, such that if the ripple is reduced due to Rr, Cr and Cac variation, the device will still work.  however, derated COUT needs to be put in by user.

    For input ripple voltage, this is only a factor if you are trying to work in a condition where input voltage is close to output voltage.  again, I would derate input capacitance by 50% worst case, user will need to do this.

    hope this makes sense.

    David.