What the 75 dB PSRR buys your 5V rail
The LD1117DT50TR is a fixed 5V output LDO from the LD1117 family, rated for 800 mA continuous output with a maximum dropout of 1.2 V at full load.
Dropout headroom and thermal budget
With a 1.2 V dropout ceiling at 800 mA, the input must stay above 6.2 V to hold regulation. The DPAK (TO-252) package's exposed tab carries the thermal dissipation; at 800 mA and a 6.5 V input, the die dissipates about 1.2 W — the tab's copper area on the PCB sets the junction temperature below the 125°C maximum.
STMicroelectronics lists the LD1117DT50TR as Active. ROHS3 compliant.