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TPS7A8001: Maximum output capacitor for the TPS7A8001

Konstantinos Petkos
Prodigy 100 points

Part Number: TPS7A8001

Hello,

I am planning to use the TPS7A8001 voltage regulator chip in my PCB design and I want to increase the PSRR at high frequencies (higher than 250 kHz).

As a result, I need to put a large output capacitor and I am thinking of using a 47u ceramic capacitor.

In the TPS7A8001 datasheet (figures 17 and 18 on page 9), there are some PSRR measurements with output capacitance of 100 uF.

So, my first question is which is the maximum output capacitor of the TPS7A8001 chip?

And also if I put a 47u ceramic capacitor at the output of the TPS7A8001 chip,  will I have to change the values of the input and the NR capacitors (1u and 10n respectively, according to the datasheet)?

Thank you in advance,

Konstantinos

  • 0
    TI__Mastermind 23361 points
    Hi Konstantinos,

    Datasheet states the device is stable with 4.7uF or larger ceramic cap. From the PSRR plot, you can see it has been tested with 100uF cap. I am not aware of tests being done with bigger than 100uF cap. 47uF cap should be okay. You will need to test the device with the cap and see the transient response to decide if it's good enough for your application. At the same time, you could consider pre-filtering your input signal for your system to achieve similar performance at the output of the LDO.

    You don't have to change the other capacitors' values with bigger output cap unless there is a need for your application.

    Regads,
    Jason Song
  • 0 in reply to Jason Song
    Prodigy 100 points

    Hi Jason,

    Thank you for your prompt reply.

    Everything is clear now.

    Best regards,

    Konstantinos