Elaborating on Tom's answer, there is a bit of a subtlety about dropout voltage.
![enter image description here](https://cdn.statically.io/img/i.sstatic.net/IXGBm.png)
The pass element is a PMOS, so when it is fully ON, it will behave as a resistor RdsON whose value depends on temperature and Vgs. This is why dropout voltage graphs in Tom's answer are all straight lines.
In dropout mode, when Vin is too low, the "opamp" shown in the internal schematic will be clipped, its output will be the lowest possible voltage to get the FET to turn on as much as possible. If we assume TI engineers are smart, then the opamp output should be able to reach ground, so the FET's Vgs is equal to the input supply voltage.
So the subtlety about dropout voltage in PMOS based LDOs is that it depends on the input voltage since that's what determines the available FET Vgs. So whatever LDO you use, make sure you look for a dropout voltage graph at Vout=3.3V which means they set the input voltage to just enough to get 3.3V on the output, and not for any other voltage which would result in a different FET Vgs.
Especially if you pick another LDO, if the only dropout voltage graph in the datasheet is measured at 5V output, it won't be the correct dropout for 3.3V output at close to 3.3V input.
Since max dropout voltage at 3.3V is 220mV for 300mA, the PMOS' maximum RdsON is about 733 mOhms, at 85°C Tj. In dropout mode, the FET is basically a resistor of at most 733 mOhms which means there is no PSRR and the output impedance is higher than when the LDO regulates properly.
So you have to be careful that the input voltage isn't too noisy and does not have voltage dips, because that will end up directly in the output. And if the load draws pulsed current, output voltage may dip too. You may need a larger output cap, so it's a good idea to place a footprint for it, even if you don't use it. This could be important if the load is sensitive to noise, and you use a LDO to give it a clean supply.
Also your slave's data pins should not be damaged until the ESD diodes conduct, which should allow for signals up to about 0.5V above its supply.