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Original question:

TPS7H2201-SP: TPS7H2201

TPS7H2201-SP: Recommended capacitance value of input bypass capacitors

Liu Yang
Expert 8755 points
Part Number: TPS7H2201-SP

Hi Team,

According to the “10 Power Supply Recommendations” at page 31 of the data sheet, 330-µF capacitor is used.
For our application, input is + 5V power supply and ripple is ±50 mV (DC/DC converter catalog value) and 4 load switches are connected in parallel.
Adding a 330 μF capacitor described in the data sheet to the input of each load switch will allow the total capacitance exceeds 1000μFwhich is the limitation of the DC/DC converter.
I wondered if there is a standard for the capacitance according to the power supply quality.

Best Regards,
Tom Liu

  • 0
    TI__Mastermind 28565 points

    Hey Tom,

    If the load switch is close to the output of the converter, the bulk output capacitance of the converter can act like the input capacitance for each of the load switches.The 330 uF caps you see in the datasheet is if the load switch has to provide the inrush current to whatever is on the output/input.

    If the load switches are "close enough" to the output capacitance of the converter for it to provide inrush current at start-up, and whatever it is supplying has input capacitance appropriate for the application, there becomes a lot less needed for there to be capacitance for the TPS7H2201-SP.

    The 330 uF is also for the full 6 A if you are working with lower currents as well.

    My recommendation is simply to make sure there won't be a large input voltage dip at start-up for input capacitnace.

    Thanks,

    Daniel