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TPS7A63-Q1: TPS7A6350 transient response

user4370495
Expert 1155 points
Part Number: TPS7A63-Q1

Dear TI:

     i  want to know what's the relationship between output capacitance  and transient response?  
input volt: 12V ,  Output volt: 5v  and the load  Current total only 130mA . output capacitance total about 10uf+0.1uf*7
when the load switch on, the output volt drop down to 4.2V ,and  Reset pin pull down.
i want to know how to choose suitable value about the output capacitance ?
thanks very much.

  • 0
    TI__Guru 55940 points
    Hi ,

    Yes, there is a relationship between output capacitance and transient response. Increasing the capacitance will reduce the magnitude of a transient response; however, the trade off is that the duration of the transient is increased.

    Essentially the load current increases, initially it will be the output capacitor(s) will supply the current to the load until the LDO can respond. This will cause the output voltage to drop as the capacitors deplete their charge. By increasing the capacitance, you will be able to supply more current with a lower drop in voltage; however, when the LDO responds, it will need to recharge the output capacitance which takes longer with additional capacitance.

    Very Respectfully,
    Ryan