What the 75 dB PSRR means for your rail
The LD1117DT33CTR delivers 75 dB PSRR at 120 Hz — that is the ripple rejection a designer needs when post-regulating a 50/60 Hz rectified supply or a switching regulator output for a sensitive analog or RF load. The 1.3 V max dropout at 800 mA sets the input-to-output headroom: you need at least 4.6 V on the input to hold 3.3 V at full current.
Dropout and quiescent current at the BOM level
At 800 mA output, the 10 mA quiescent current is the overhead the input supply must cover — it is not negligible in battery-powered designs but is typical for a general-purpose LDO at this current. The over-current and over-temperature protection are built in, so no external current-limit resistor is needed.