A 150 mA low-dropout regulator tuned for low output noise, in SOT-23-5. A bypass pin takes a small capacitor that filters the internal reference, dropping output noise to levels that suit RF, ADC references, PLLs, and sensor front ends where a plain LDO would inject too much hash. It has a logic enable (ON/OFF) for power sequencing and shutdown, good line and load regulation, and needs only small ceramic capacitors. This page is the fixed 3.3 V version; the family covers 1.8 to 5 V. Input up to 16 V.

Pinout

Pin	Name	Type	Function
1	VIN	power_in	Input supply pin. Range 2.5V to 16V (new chip) or 2.2V to 16V (legacy). Requires a 1µF or larger input capacitor from this pin to ground.
2	GND	power_in	Ground reference for the regulator. Carries the quiescent (GND pin) current, up to about 890µA at 150mA load.
3	ON/OFF	input	Active-high enable input for the LDO. Drive high (≥1.6V) to enable the regulator, low (≤0.15V) to place the device in shutdown. Tie to VIN if unused; do not leave floating. Withstands up to 16V (legacy) or 18V (new chip).
4	BYPASS	passive	Reference-voltage bypass pin used to lower output noise. Connect an external capacitor (typically 10nF) from BYPASS to GND to achieve the specified 30µVRMS noise performance and improve PSRR.
5	VOUT	power_out	Regulated output of the LDO, delivering up to 150mA at the factory-fixed output voltage (1.2V-5.0V in 100mV steps for new chip). Requires an output capacitor of at least 2.2µF (new chip) or 1µF effective, with ESR ≤1Ω for stability.

Key specifications

Parameter	Value
Type	Low-noise LDO regulator
Output current	150 mA
Output voltage	3.3 V (fixed, this variant)
Noise	low (bypass-pin filtered)
Enable	ON/OFF logic pin
Dropout	~280 mV at 150 mA
Input voltage	up to 16 V
Package	SOT-23-5

Ordering variants

Same part, different packaging or reel option.

LP2985AIM5-3.3 (SOT-23-5)
LP2985IM5X-3.3 (SOT-23-5, tape & reel)

CAD (KiCad official)

Symbol: Regulator_Linear:LP2985-3.3
Footprint: Package_TO_SOT_SMD:SOT-23-5
3D model: SOT-23-5 (KiCad packages3D)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

Datasheet: Texas Instruments datasheet (43 pp, sha256 bd79c7c5719a63c1, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF