What the key ratings mean for the BOM
The L78L15ABZ-AP: The 39 dB PSRR at 120 Hz tells you how much ripple from a full-wave rectified mains supply gets through to the output. At 39 dB, the output ripple is about 1.1 % of the input ripple — good enough for a 15 V rail feeding a comparator or a small relay, but not for a precision ADC reference where you would want 60+ dB. The built-in protection features — over-current, over-temperature, and short-circuit — mean the regulator survives a dead short on the output without external crowbar circuitry; the thermal shutdown cycles the output until the fault clears. At 100 mA load, the efficiency is roughly 15/35 ≈ 43 % at max input, so the power dissipated in the TO-92-3 package must be considered: at 35 V in and 100 mA out, the dropout is 20 V × 0.1 A = 2 W, which exceeds the TO-92's thermal capability without a heatsink. For continuous operation, keep the input-to-output differential below about 10 V or derate the output current.
Through-hole TO-92-3 — board-fit and sourcing
The L78L15ABZ-AP comes in a TO-226-3 / TO-92-3 package with formed leads. It is a through-hole part — the leads are on 0.1-inch pitch, so it fits standard perfboard or a 0.1-inch grid PCB footprint. The "-AP" suffix indicates Tape & Box (TB) or Cut Tape (CT) packaging, not reel. If your assembly line is pick-and-place only, the surface-mount sibling L78L12ABD-TR shares the same die but in an SO-8 package — though that is a 12 V part, not 15 V.