3.3 V rail for noise-sensitive loads — PSRR and dropout headroom
The LP2985-33DBVRM3 is a fixed 3.3 V output LDO delivering 150 mA with a maximum dropout of 0.575 V at full load — the input rail must stay above 3.875 V to maintain regulation, which a standard 5 V supply clears with 1.125 V of headroom. PSRR spans 78 dB at 1 kHz down to 45 dB at the same frequency — this is the rejection profile for switching-regulator ripple in the 1 kHz band, typical of a poorly filtered boost converter feeding the analog rail. Quiescent current is 95 µA, so the regulator's own draw stays under 0.1 mA in light-load or shutdown scenarios — relevant for battery-backed RTC or sensor nodes that spend most of their time in idle.
16 V input range and protection set — wide-VIN coverage without external clamps
Input voltage maxes at 16 V, so the part can be fed from a 12 V industrial bus, a 9 V battery, or a 5 V logic rail without a pre-regulator — the internal pass FET's breakdown margin covers the full range. On-chip protection includes over-current limiting, thermal shutdown, and under-voltage lockout (UVLO) — the UVLO threshold prevents the output from sourcing current into a rail that hasn't fully come up, which avoids latch-up on the downstream load.
SOT-23-5 footprint and supply format
The LP2985-33DBVRM3 comes in an SOT-23-5 (SC-74A) package — the pinout is standard for this class: input, ground, enable, output, and a no-connect or bypass pin depending on the variant. The 0.95 mm pitch and 2.9 x 1.6 mm body fit a 2-layer board with a ground pour under the package. Available in Tape & Reel (TR) or Cut Tape (CT) — the TR format is the standard reel for automated pick-and-place; CT is for prototype or low-volume builds where the reel fee isn't justified.
Active lifecycle and sourcing posture
RoHS3 compliant per the manufacturer's declaration — no exemptions for lead in solder or other restricted substances under the current EU directive.