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Clarification needed : Choosing a proper output capacitor for TL751L12

Jebas Paul Daniel
Prodigy 40 points

Hi,

In the datasheet of TL751L12, Fig 4 shows the stability of the regulator with respect to the ESR of output capacitor.
As per datasheet information the ESR should be less than 0.4 to have a good stability.
But, usually the ESR of capacitor is mentioned at particular frequency. For a ceramic capacitor ESR is mentioned at 100KHz.

My question is as follows;

1. The ESR information given in the Fig 4 of datasheet doesn't have any frequency information.Please let me know the frequency information of ESR, i.e at what frequency the ESR of capacitance should be <0.4 ohm.
2. I have selected T495X106M035ATE250 capacitor as a load capacitor.Please give your comments.

Thanks,

Jebas

  • 0
    TI__Guru**** 164436 points

    Jebas,

    100kHz is a good test value.

    The capacitor zero for 10uF and 0.4 ohms is 40 kHz.
    The capacitor zero for 10uF and 0.25 ohms is 64 kHz.

    The ESR is needed to create a zero before the unity bandwidth, but not too much before.
    The capacitor ESR meets the data sheet recommendation.