AO3400 — N-Channel Logic-Level Enhancement Mode MOSFET (SOT-23)

Overview

The AO3400 (AO3400A) is an ultra-popular N-channel logic-level power MOSFET manufactured by Alpha & Omega Semiconductor. Packaged in a subminiature SOT-23 enclosure, it delivers exceptionally high current capability and extremely low $R_{DS(on)}$ resistance in an SMD footprint.

Featuring a drain-source breakdown voltage of $30\text{ Volts}$ , continuous drain current handling up to $5.7\text{ Amps}$ , and an $R_{DS(on)}$ of just $33\text{ m}\Omega$ at $4.5\text{V}$ (and $52\text{ m}\Omega$ at $2.5\text{V}$ ), the AO3400 is widely used in battery-powered electronics, Li-ion protection circuits, high-current load switches, motor drivers, and LED strip controllers driven by 3.3V and 2.5V microcontrollers.

Quick reference


Transistor Type	N-Channel Logic-Level Enhancement Mode MOSFET
Package	SOT-23 (3-pin SMD)
Drain-Source Voltage ( $V_{DSS}$ )	$30\text{ V}$ max
Continuous Drain Current ( $I_D$ )	$5.7\text{ A}$ at $V_{GS} = 10\text{V}$ ( $5.0\text{ A}$ at $4.5\text{V}$ , $2.8\text{ A}$ at $2.5\text{V}$ )
Gate Threshold Voltage ( $V_{GS(th)}$ )	$0.6\text{ V}$ min to $1.5\text{ V}$ max ( $1.0\text{ V}$ typical)
On-State Resistance ( $R_{DS(on)}$ )	$28\text{ m}\Omega$ at $10\text{V}$ / $33\text{ m}\Omega$ at $4.5\text{V}$ / $52\text{ m}\Omega$ at $2.5\text{V}$
Pulsed Drain Current ( $I_{DM}$ )	$30\text{ A}$
Total Power Dissipation	$1.4\text{ W}$ ( $T_A = 25^\circ\text{C}$ )

Pinout (SOT-23 Package)

Looking at the top of the SOT-23 surface-mount component with single lead on top:

text

               ┌─────────┐
               │    3    │  (DRAIN)
               └─┐     ┌─┘
                 │AO340│
               ┌─┘     └─┐
               │ 1     2 │
               └─────────┘
            (GATE)   (SOURCE)

Pin	Name	Description
1	`GATE` (`G`)	Gate control input (Connect to MCU GPIO pin)
2	`SOURCE` (`S`)	Source terminal (Ground reference 0 V)
3	`DRAIN` (`D`)	Drain terminal (Low-side load connection)

Specifications

Parameter	Symbol	Min	Typ	Max	Unit	Conditions
Drain-Source Breakdown Volts	$V_{(BR)DSS}$	30	—	—	V	$V_{GS} = 0\text{V}, I_D = 250\ \mu\text{A}$
Gate Threshold Voltage	$V_{GS(th)}$	0.6	1.0	1.5	V	$V_{DS} = V_{GS}, I_D = 250\ \mu\text{A}$
On-Resistance ( $V_{GS}=10\text{V}$ )	$R_{DS(on)}$	—	22	28	mΩ	$V_{GS} = 10\text{V}, I_D = 5.7\text{A}$
On-Resistance ( $V_{GS}=4.5\text{V}$ )	$R_{DS(on)}$	—	26	33	mΩ	$V_{GS} = 4.5\text{V}, I_D = 5.0\text{A}$
On-Resistance ( $V_{GS}=2.5\text{V}$ )	$R_{DS(on)}$	—	38	52	mΩ	$V_{GS} = 2.5\text{V}, I_D = 2.8\text{A}$
Total Gate Charge	$Q_g$	—	7.2	10.0	nC	$V_{GS} = 4.5\text{V}, V_{DS} = 15\text{V}$

Common mistakes

Exceeding package thermal dissipation limit ( $1.4\text{ W}$ ): While the die can handle up to $5.7\text{ A}$ , running continuous high currents on a small PCB without sufficient copper pour heatsink area can cause thermal throttling.
Applying Gate voltage $> 12\text{V}$ : The absolute maximum Gate-Source voltage ( $V_{GS}$ ) rating for the AO3400 is $\pm 12\text{V}$ (unlike standard power FETs rated for $\pm 20\text{V}$ ). Driving the gate directly from $15\text{V}$ or $24\text{V}$ rails destroys the gate oxide layer.

Notes

AO3400 vs 2N7002: AO3400 has $33\text{ m}\Omega$ $R_{DS(on)}$ and $5.7\text{ A}$ rating; 2N7002 has $5.0\ \Omega$ $R_{DS(on)}$ and $115\text{ mA}$ rating. AO3400 is suited for heavy load switching; 2N7002 is for signal switching.

Interface	Sub-1.8V to 10V Gate Drive Compatible
Package	SOT-23 (3-pin SMD)