TPS7A47: Looking for low-dropout regulators (LDOs) to reduce switch-mode power supply ripple

Hello,

I am looking for low-dropout regulators (LDOs) to reduce switch-mode power supply ripple by TPS61251 Boost Converter with typical operating frequency: 3.5 MHz

It is the application in voltage rail for high-precision ADCs such as ADS1260.

The input voltage is +5.5V and the output voltage is +5V.

Here are the questions:

1. Which is the most important feature in the datasheet should I concern? (PSRR, Output Range, … etc.)
2. I chose TPS7A47x because of the high PSRR at 3.5MHz. Is TPS7A470x ideal choose or other suggestion?
   
   

   -Jax