MT3406 from Aerosemi, 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	EN	input	Chip Enable input. Drive above 1.5V (VENH) to turn on the converter; drive below 0.4V (VENL, 0.3V typ) to shut it down (<1µA shutdown current). Do not leave floating.
2	GND	power_in	Analog ground pin. Common return for the IC and the input/output decoupling capacitors.
3	SW	output	Power switch output; switch node connecting to the external inductor. Tied to the drains of the internal P-channel and N-channel MOSFET switches. RDS(on) ~300mΩ typ, peak current limit 2A.
4	VIN	power_in	Power supply input, 2V to 6V (6.5V abs max). Must be closely decoupled to GND with a 4.7µF or greater ceramic capacitor.
5	FB	input	Output voltage feedback input. External resistor divider (R1/R2) from VOUT sets the output voltage per VOUT = 0.6V * (1 + R1/R2). Internal reference VFB = 0.600V (±2%).

Key specifications

Parameter	Value
Manufacturer	Aerosemi
Package	SOT-23-5
Category	PMIC
Pins	5

CAD (KiCad official)

Symbol: MT3406
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
`mt3406.step`	85 KB	You want the bare part, or you mark your own boards.
`mt3406-etched.step`	1.4 MB	You want the part with `MT3406` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 334 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: Aerosemi datasheet (9 pp, sha256 b0ca202562d99c5f, retrieved 2026-08-17, tier: lcsc)
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