Dropout and thermal — the real-world constraints
Maximum dropout is 1.2 V at 800 mA output. That means with a 2.85 V rail the input must stay above 4.05 V worst-case — a 5 V rail is fine, but a 3.3 V rail won't regulate. The TO-252 (DPak) package has an exposed tab on the drain; the datasheet copper area under that tab sets the junction-to-ambient thermal resistance. At 800 mA and 1.2 V dropout the device dissipates nearly 1 W — plan a 1 in² copper pad on a 2-layer board to keep the junction below the 125°C ceiling.
TI has ended production; no last-time-buy window is open. New builds need an alternative — the closest pin-compatible option is the LM1117DT-3.3/NOPB if the load can tolerate 3.3 V, or a different fixed-voltage variant in the same family if 2.85 V is mandatory. For existing BOM lines, independent distribution holds remaining inventory.