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TPS564201: Output Ripple

vishal kakade22
Intellectual 355 points
Part Number: TPS564201

I am using Tps564201 for a driving a load that requires 1.3V - 1.5 Amp, i have designed the output filter according to TI webench design and the datasheet of the IC.

But there is a ripple of 600mV in the output.  and output voltage increases slightly.

Can i over design the filter in order to Reduce the ripple ?

And the  flyback diode is not present in this design which is usally present in the buck converters. so if i increase inductor and capacitor values  should  i put that flyback diode or what will be the effect of over designing the filter?

  • 0
    TI__Mastermind 18510 points
    Hi,

    600mv is a big value, Could you please upload your simulation schematic?
    Recommend you follow the Table2 component value for LC filter design, which decides the LC double pole corner.
    such as for 1.3V, L is not over 4.7uh, Cout is not over 68uF.
    if over the filter maybe the LC pole goes to lower frequency, which maybe cause the loop not stable.
    About the flyback diode, do you mean the diode between SW to Ground? If so, i this this should be no effect.

    BR,
    yuchang
  • 0 in reply to Yuchang Zhang
    Intellectual 355 points
    HI,

    Schematic is same as given in the datasheet.
    How can i do the frequency analysis and check the positions of the poles?

    and if i use the filter as per datasheet, what about the other capacitors which are parallel to this in the board?
    how will they affect the stability of the loop?
  • 0 in reply to vishal kakade22
    TI__Guru**** 191445 points
    The common way to check the loop response is to insert a 50 ohm resistor between VOUT and R1 (referencing the DS fig 14 schematic) and use a network analyzer to measure the loop response. Generally, the further away the additional capacitance is from the converter point of regulation, the lees effect they have on the total loop. If they are close by, you will need to take them into account.