A 30 V N-channel logic-level MOSFET in SOT-23, one of the most-used surface-mount switching FETs in modern designs. Its very low on-resistance (about 28 milliohm at VGS=10 V, and still low at 4.5 V) and 5.7 A rating let it switch power loads, act as a low-side gate for LEDs, motors, and relays, or serve as a load switch, all while turning fully on from 3.3 V or 5 V logic. In the tiny SOT-23 it replaces bulkier through-hole MOSFETs on space-constrained boards. Pinout is G, S, D. It is a near drop-in for the 2N7002 at much higher current.

Pinout

Pin	Name	Type	Function
1	G	input	Gate. Controls conduction between drain and source. Gate threshold voltage VGS(th) typ 1.05V (0.65V-1.45V). Absolute maximum VGS = ±12V. Input capacitance Ciss ≈ 630 pF.
2	S	passive	Source. Current return terminal for the N-channel MOSFET. Body diode anode (body-diode forward voltage typ 0.7V, max 1V at IS=1A).
3	D	passive	Drain. High-side terminal of the N-channel MOSFET. Absolute maximum VDS = 30V. Continuous drain current ID = 5.7A at TA=25°C, pulsed IDM = 30A. Body diode cathode.

Key specifications

Parameter	Value
Type	N-channel MOSFET (logic-level)
Drain-source (VDS)	30 V
RDS(on)	~28 mΩ at VGS=10 V (~50 mΩ at 4.5 V)
Continuous drain current	5.7 A
Gate threshold	1-1.7 V (logic-level)
Power dissipation	1.4 W
Pinout	G-S-D
Package	SOT-23

Ordering variants

Same part, different packaging or reel option.

AO3400A (SOT-23)
AO3400 (SOT-23, prior rev)

CAD (KiCad official)

Symbol: Transistor_FET:AO3400A
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 9c60d0b6c1ddc760, 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