2N7002 — Small-Signal N-Channel Enhancement Mode MOSFET (SOT-23)

Overview

The 2N7002 is a widely used small-signal N-channel Enhancement Mode MOSFET IC packaged in a 3-pin surface-mount SOT-23 enclosure. It is the SMD counterpart to the classic through-hole 2N7000 transistor.

Designed for low-power signal switching, LED drive, small relay coil activation, and bidirectional $3.3\text{V} \leftrightarrow 5.0\text{V}$ $I^2C$ logic level shifters, the 2N7002 handles drain-source voltages up to $60\text{ Volts}$ and continuous drain currents up to $115\text{ mA}$ . With a low gate threshold voltage ( $V_{GS(th)}$ of $1.0\text{V} \dots 2.5\text{V}$ ), it drives directly from 3.3V and 5V microcontroller GPIO pins.

Quick reference


Transistor Type	Small-Signal N-Channel Enhancement Mode MOSFET
Package	SOT-23 (3-pin SMD)
Drain-Source Voltage ( $V_{DSS}$ )	$60\text{ V}$ max
Continuous Drain Current ( $I_D$ )	$115\text{ mA}$ continuous ( $300\text{ mA}$ pulsed)
Gate-Source Voltage ( $V_{GS}$ )	$\pm 20\text{ V}$ max ( $\pm 40\text{ V}$ peak transient)
Gate Threshold Voltage ( $V_{GS(th)}$ )	$1.0\text{ V}$ min to $2.5\text{ V}$ max ( $1.8\text{ V}$ typical)
On-State Resistance ( $R_{DS(on)}$ )	$5.0\ \Omega$ at $V_{GS} = 10\text{V}$ / $7.5\ \Omega$ at $V_{GS} = 4.5\text{V}$
Turn-on / Turn-off Time	$7\text{ ns}$ turn-on / $11\text{ ns}$ turn-off

Pinout (SOT-23 Package)

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

text

               ┌─────────┐
               │    3    │  (DRAIN)
               └─┐     ┌─┘
                 │2N702│
               ┌─┘     └─┐
               │ 1     2 │
               └─────────┘
            (GATE)   (SOURCE)

Pin	Name	Description
1	`GATE` (`G`)	Gate control input (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	$V_{(BR)DSS}$	60	—	—	V	$V_{GS} = 0\text{V}, I_D = 10\ \mu\text{A}$
Gate Threshold Voltage	$V_{GS(th)}$	1.0	1.8	2.5	V	$V_{DS} = V_{GS}, I_D = 250\ \mu\text{A}$
Zero Gate Voltage Current	$I_{DSS}$	—	—	1.0	µA	$V_{DS} = 60\text{V}, V_{GS} = 0\text{V}$
On-Resistance ( $V_{GS}=10\text{V}$ )	$R_{DS(on)}$	—	3.5	5.0	Ω	$V_{GS} = 10\text{V}, I_D = 500\text{mA}$
On-Resistance ( $V_{GS}=4.5\text{V}$ )	$R_{DS(on)}$	—	4.5	7.5	Ω	$V_{GS} = 4.5\text{V}, I_D = 75\text{mA}$
Total Power Dissipation	$P_D$	—	—	350	mW	$T_A = 25^\circ\text{C}$

Common mistakes

Attempting to drive high-current loads (>150mA): The 2N7002 has an $R_{DS(on)}$ of up to $7.5\ \Omega$ at $4.5\text{V}$ gate drive. Driving heavy loads generates excessive heat for an SMD SOT-23 footprint. For loads $>200\text{ mA}$ , use a high-current SMD MOSFET like the AO3400 ( $33\text{ m}\Omega$ ).
Leaving gate floating: Always place a $10\text{ k}\Omega$ pull-down resistor from Gate to Source (GND) to prevent floating electrostatic charges from inadvertently triggering the FET.

Notes

2N7002 vs 2N7000 vs BSS138: 2N7002 is SOT-23 SMD ( $115\text{ mA}$ ); 2N7000 is TO-92 through-hole ( $200\text{ mA}$ ); BSS138 is SOT-23 SMD with lower threshold ( $1.3\text{V}$ typ) optimized for 3.3V level shifters.

Interface	Gate-Source Logic Drive (3.3V and 5V Compatible)
Package	SOT-23 (3-pin SMD)