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TPS63060 / Concern at using lower Cout than recommended

S.Satoshi
Guru 21685 points
Other Parts Discussed in Thread: TPS63060

Hi,

I'd like to know the concern at using lower Cout than recommended in Table 2 in TPS63060 datasheet. My customer has only limited space to place 44uF of Cout so actual capacitance will be lower due to tolerance and bias voltage de-rating.They are concerning of unstable operation at using lower Cout.

Best Regards,

Sonoki / Japan Disty

 

  • 0
    TI__Expert 8420 points

    I would not use a lower capacitance than 44uF. As stated in the DS this value takes in account  the biais voltage de-rating. Therefore I would make sure I have a minimum effective output capacitance of  ~25uF. 

  • 0 in reply to Sabrina
    Guru 21685 points
    Hi Sabrina,

    Thank you for your comment. I will recommend my customer to use output capacitor that has effective capacitance higher than 22uF (50% of 44uF).

    Best Regards,
    Sonoki
  • 0 in reply to S.Satoshi
    Guru 21685 points
    Hi Sabrina,

    The table2 recommend L and Cout value, then can you please let me know what load current is assuming for these value? Now I'd like to know if I can use smaller Cout at light load application. Do you think the effective capacitance higher than 22uF is necessary for following requirement?

    Vin = 5.5V - 10V
    Vout = 5.7V
    Iout(max) = 80mA
    L = 1.2uH


    And also, can you please let me know the concern when the smaller Cout is used?


    Best Regards,
    Sonoki
  • 0 in reply to S.Satoshi
    TI__Expert 8420 points

    Hi,

    These values are given for maximum current.

    If you are using only 80mA and the device operates in PFM, in this case you could eventually use a smaller effective capacitance  but  I would first try to decrease it and test it. I woud also check if the output is stable for load transient.

    If you use smaller Cout the output may be unstable in worst case, or at least you would see higher output ripple.