2N7000 — Small-Signal N-Channel Enhancement Mode MOSFET

Overview

The 2N7000 is a universally used small-signal N-channel Enhancement Mode MOSFET IC manufactured by ON Semiconductor, Microchip, and STMicroelectronics. Packaged in a compact 3-pin TO-92 enclosure, it is often described as the "FET equivalent of the 2N3904 NPN transistor".

Designed for low-power signal switching, LED indicators, small relay coil drivers, and bidirectional $3.3\text{V} \leftrightarrow 5.0\text{V}$ $I^2C$ logic level shifters, the 2N7000 handles drain-source voltages up to $60\text{ Volts}$ and continuous drain currents up to $200\text{ mA}$ . With a low gate threshold voltage ( $V_{GS(th)}$ of $0.8\text{V} \dots 3.0\text{V}$ ), it turns on directly from 3.3V and 5V microcontroller GPIO output pins.

Quick reference


Transistor Type	Small-Signal N-Channel Enhancement Mode MOSFET
Package	TO-92 (Flat face front, leads pointing down) / SOT-23 (2N7002)
Drain-Source Voltage ( $V_{DSS}$ )	$60\text{ V}$ max
Continuous Drain Current ( $I_D$ )	$200\text{ mA}$ continuous ( $500\text{ mA}$ pulsed)
Gate-Source Voltage ( $V_{GS}$ )	$\pm 20\text{ V}$ max ( $\pm 40\text{ V}$ peak transient)
Gate Threshold Voltage ( $V_{GS(th)}$ )	$0.8\text{ V}$ min to $3.0\text{ V}$ max ( $1.8\text{ V}$ typical)
On-State Resistance ( $R_{DS(on)}$ )	$5.0\ \Omega$ at $V_{GS} = 10\text{V}$ / $5.3\ \Omega$ at $V_{GS} = 4.5\text{V}$
Turn-on / Turn-off Time	$10\text{ ns}$ turn-on / $10\text{ ns}$ turn-off (High speed switching)

Pinout (TO-92 Package)

Looking at the flat face of the TO-92 package with leads pointing down:

text

        ┌─────────────┐
        │   2N7000    │  (Flat Package Face)
        └─┬───┬───┬───┘
          1   2   3
          S   G   D

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

Warning

Pinout Warning: 2N7000 vs BS170 Pinouts!

2N7000 (TO-92): Pin 1 = Source, Pin 2 = Gate, Pin 3 = Drain (S-G-D).
BS170 (TO-92): Pin 1 = Drain, Pin 2 = Gate, Pin 3 = Source (D-G-S).
Always double-check part numbers before plugging replacement FETs into breadboards.

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	$V_{GS(th)}$	0.8	1.8	3.0	V	$V_{DS} = V_{GS}, I_D = 1\text{mA}$
Zero Gate Voltage Current	$I_{DSS}$	—	—	1.0	µA	$V_{DS} = 48\text{V}, V_{GS} = 0\text{V}$
On-Resistance ( $V_{GS}=5.0\text{V}$ )	$R_{DS(on)}$	—	4.0	5.3	Ω	$V_{GS} = 4.5\text{V}, I_D = 75\text{mA}$
Power Dissipation	$P_D$	—	—	400	mW	$T_A = 25^\circ\text{C}$

Bidirectional 3.3V to 5V $I^2C$ Level Shifter Circuit

A single 2N7000 MOSFET converts a $3.3\text{V}$ $I^2C$ bus signal (SDA/SCL) to a $5.0\text{V}$ $I^2C$ bus line:

text

        +3.3V Power Rail                    +5.0V Power Rail
              │                                   │
      [ R1 = 10kΩ Pullup ]               [ R2 = 10kΩ Pullup ]
              │                                   │
  3.3V MCU ───┴─── [Pin 1: SOURCE] ────┐          ├─── 5V I2C Sensor (SDA)
                        2N7000         │          │
                   [Pin 2: GATE] ──────┼── +3.3V  │
                                       │          │
                   [Pin 3: DRAIN] ─────┴──────────┘

Common mistakes

Attempting to drive high-current loads (>200mA): The 2N7000 has a relatively high $R_{DS(on)}$ resistance of $5.0\ \Omega$ . Driving a $500\text{ mA}$ load creates $I^2 R = (0.5)^2 \times 5 = 1.25\text{ Watts}$ of dissipation, instantly overheating the $400\text{ mW}$ TO-92 package. For loads $>200\text{ mA}$ , use a power MOSFET like the IRLZ44N.
Leaving gate pin floating: MOSFET gates act as tiny capacitors. Leaving the gate disconnected allows static electricity to turn the transistor partially ON. Include a $10\ \text{k}\Omega$ pull-down resistor to GND.

Notes

2N7000 vs 2N7002 vs BS170: 2N7000 is TO-92 (S-G-D); 2N7002 is SOT-23 SMD version; BS170 is TO-92 with reversed (D-G-S) pinout.

Interface	Gate-Source Logic Drive (3.3V and 5V Compatible)
Package	TO-92 / SOT-23 (2N7002)