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TPS563219A: How do we calculate max output capacitor value?

Li Chen92
Expert 3040 points
Part Number: TPS563219A

Hi TI expert

May I have a question for max output capacitor value.
TPS563219A: There is lilited max output capacitor value(from 20uF to 68uF)
We implement FET and Coil in this power plane.
How do we caluculate behind these parts(FET and Coil)?
Can we devide or ignore it? or to add?

Best regards,

Thomas

  • 0
    TI__Intellectual 1801 points

    Hi Thomas,

    I'm not clear about your questions. Do you want to know how to select the LC filter values?  Below are recommended values, and you can find it from datasheet. 

    Regards,

    Jared.

  • 0 in reply to Jiandong Liu
    TI__Expert 3040 points

    Hi Jared

    Table2 is described limitation of total capacitor on the output power plane.
    Now our total capacitor value is over the 68uF.
    So If we think the workaround reduce it. If we out put power pass through via FET or inductor, Can we ignore the capacitor value over FET or inductor? or not ignore?

     

    Best regards,

    Thomas

  • 0 in reply to Li Chen92
    TI__Intellectual 1801 points

    Hi Thomas,

    We give recommended capacitor values for stability considerations. If you use a capacitor within 20-68uF, the double pole of LC filter is located nearby the high frequency zero introduced by D-CAP2Tm, which results adequate phase margin and good stability. But if you use a capacitor large than 68uF, that doesn't mean it must be unstable. A slightly larger capacitor is still acceptable. Could you share the schematic to me for review?

    Ragards,

    Jared.