LM3671MFX-3.3 from Texas Instruments, in a SOT-23-5. Pinout and pin descriptions extracted from the manufacturer datasheet by ds2sf; symbol, footprint, and 3D from KiCad-official CAD.

Pinout

Pin	Name	Type	Function
1	VIN	power_in	Power supply input, 2.7 V to 5.5 V. Connect directly to the input filter (ceramic) capacitor. Absolute maximum 6 V to GND.
2	GND	power_in	Device ground reference. Return path for input capacitor and internal NFET synchronous rectifier.
3	EN	input	Enable input. Device is in shutdown mode when V(EN) < 0.4 V and enabled when V(EN) > 1 V. Do not leave floating; absolute maximum GND-0.2 V to VIN+0.2 V.
4	FB	input	Feedback analog input. For the fixed 3.3 V version, connect directly to the output filter capacitor at VOUT; the internal resistor divider sets the regulation point (internal dividers are disabled on the adjustable version).
5	SW	output	Switching node to the internal PFET high-side switch and NFET synchronous rectifier. Connect through the 2.2 uH power inductor to VOUT. Handles up to 600 mA load current.

Key specifications

Parameter	Value
Manufacturer	Texas Instruments
Package	SOT-23-5
Category	PMIC
Pins	5

Ordering variants

Same part, different packaging or reel option.

LM3671MFX-3.3
LM3671MFX-3.3TL
LM3671MFX-3.3TLX
LM3671MFX-3.3SD
LM3671MFX-3.3SDX

CAD (KiCad official)

Symbol: LM3671MFX-3.3
Footprint: Package_TO_SOT_SMD:SOT-23-5
3D model: SOT-23-5 (KiCad packages3D, STEP)

3D model downloads

Two STEP files. Same geometry, different body top:

File	Size	Use it when
`lm3671mfx-3-3.step`	85 KB	You want the bare part, or you mark your own boards.
`lm3671mfx-3-3-etched.step`	1.9 MB	You want the part with `LM3671MFX-3.3` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 494 faces against 102 in the bare model. It survives export, section views, and rendering in any CAD tool, and it drops straight into KiCad or Fusion with no extra setup.

Provenance

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

Datasheet: Texas Instruments datasheet (38 pp, sha256 c241e858da248679, 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