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TPS84620 Resistor and Cap Settings

John Kasson
Prodigy 90 points
Other Parts Discussed in Thread: TPS84620

Hello,

    In my design I'm using a TPS84620 to produce 2.5V and I want to make sure I get the resistor and cap settings correct.

   On Table 1 it shows for 2.5V that Rrt should be set 1K ohm while Table 2. says it should be open, which is correct? 

   On Table 3 it says to use a minimum of 200uF on the output of the power supply but on Table 4 it shows a configuration that is only 147uF, which is correct?

    Is there any significant difference between running with two separate grounds for agnd and pgnd vs just having one single ground?

Thank you,

John Kasson

  • 0
    TI__Mastermind 28020 points

    Hi John,

    For the Rrt, either will work fine, see Table 7. I would recommend using the 1kΩ for slightly higher frequency and reduced ripple, but if you want to save the component, it will operate correctly by leaving it open.

    For output capacitance, I recommend using a minimum of 200uF for 2.5V.

    By keeping the AGND and PGND separate and only connecting at one point, it keeps the power switching current from flowing through the AGND signals of the device. It also eliminates the potential for ground loops.