P-channel enhancement-mode MOSFET in a SOT-23 package, using trench technology for low on-resistance (<50 mohm at VGS = -10 V) and low gate charge. Rated -30 V drain-source and up to -4 A, it turns on with gate drive as low as -2.5 V, which suits high-side load switches and reverse-polarity protection from a 3.3-5 V rail. Source ties to the positive rail, drain to the load; the body diode runs source-to-drain.

Pinout

Pin	Name	Type	Function
1	G	input	Gate. Control terminal for the P-channel MOSFET. Gate threshold voltage VGS(th) = -0.5V to -1.3V (typ -0.9V). Absolute maximum VGS = ±12V. Input capacitance Ciss = 645pF typ.
2	S	passive	Source. Current-return terminal for the P-channel MOSFET. Typically tied to the positive supply rail in high-side load-switch configurations. Body diode anode is internally connected here (VSD typ -0.7V at IS=-1A).
3	D	passive	Drain. Switched current terminal for the P-channel MOSFET. VDS absolute maximum -30V; continuous ID up to -4A at TA=25°C. Body diode cathode is internally connected here.

Key specifications

Parameter	Value
Type	P-channel enhancement-mode MOSFET
Drain-source voltage (VDS)	-30 V
Continuous drain current (ID)	-4 A @ 25 °C
On-resistance (RDS(on))	<50 mΩ @ VGS = -10 V
Gate threshold (VGS(th))	-0.5 to -1.3 V (typ -0.9 V)
Gate-source voltage (VGS)	±12 V
Input capacitance (Ciss)	645 pF typ
Package	SOT-23
Body (L×W×H)	2.9 × 1.3 × 1.1 mm

Ordering variants

Same part, different packaging or reel option.

AO3401A (SOT-23, tape & reel)

CAD (KiCad official)

Symbol: Transistor_FET:AO3401A
Footprint: Package_TO_SOT_SMD:SOT-23
3D model: SOT-23 (KiCad packages3D)

Provenance

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

Datasheet: Alpha & Omega Semiconductor datasheet (5 pp, sha256 0d8e3261ae280e00, retrieved 2026-08-17, tier: manufacturer)
Extractor: ds2sf (Claude) — every pin and dimension is cited to a datasheet page; refuses to fabricate.
CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF