3.3 V fixed LDO — 1 A output, 1.3 V max dropout
The STMicroelectronics LD1117AS33TR is a single-output, positive fixed LDO voltage regulator delivering a regulated 3.3 V at up to 1 A. It comes in a surface-mount SOT-223 package.
Dropout headroom — the number that bites you
The 1.3 V max dropout at 1 A is the spec to check first when sizing the input rail. At lower loads the dropout drops, but the worst-case figure governs.
Protection and stability
Built-in over-current and over-temperature protection cover the usual fault cases: a shorted load or a lost heatsink. Input and output capacitors are required for stability.
STMicroelectronics lists the LD1117AS33TR as Active. The part is ROHS3 compliant. For new designs or production replenishment, the supply channel is stable — no urgency to stockpile or qualify a drop-in replacement.