MT3540-F23 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	SW	output	Power switch output; drain of the internal NMOS power switch (RDS(on) ≈ 0.5Ω, 1.5A current limit). Connect the boost inductor and Schottky rectifier diode here. SW can swing between GND and 28V.
2	GND	power_in	Device ground return. Connect directly to a solid ground plane for heat sinking and noise protection; the input and output capacitor ground returns should terminate close to this pin.
3	FB	input	Feedback input to the internal error amplifier. Internal reference is 1.23V for the MT3540-F23 variant. Set the output voltage with an external resistor divider from VOUT to FB to GND: VOUT = 1.23V × (1 + R1/R2). Input bias current ≈ -10 nA (typ).
4	EN	input	Regulator on/off control input. Drive high (VIH ≥ 1.5V) to enable the converter, low (VIL ≤ 0.4V) to shut it down (IQ ≈ 0.1µA). Tie to VIN for automatic startup. Absolute maximum -0.3V to 6V.
5	VIN	power_in	Input supply pin, 2.5V to 5.5V operating range (6V absolute max). Must be locally bypassed with a low-ESR ceramic capacitor (≥1µF, X5R/X7R recommended) placed close to the pin.

Key specifications

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

Ordering variants

Same part, different packaging or reel option.

MT3540-F23

CAD (KiCad official)

Symbol: MT3540-F23
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
`mt3540-f23.step`	85 KB	You want the bare part, or you mark your own boards.
`mt3540-f23-etched.step`	1.9 MB	You want the part with `MT3540-F23` already on it.

The marking in the etched file is real recessed geometry cut into the solid, not a texture or a decal: 461 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 (8 pp, sha256 9c75dfb0f41b8042, 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