IRF520 MOSFET driver module
A breakout board that puts the IRF520 behind screw terminals and a gate resistor, used to PWM or switch 12V and 24V DC loads such as LED strips, small motors, pumps, and solenoids from a single microcontroller pin.
IRF520 MOSFET
N-channel enhancement-mode power MOSFET in a TO-220 package, rated 100V and 9.2A for switching DC loads.
What is the IRF520 MOSFET?
The IRF520 is an N-channel enhancement-mode power MOSFET supplied in a through-hole TO-220AB package. It blocks up to 100V drain-to-source, carries a continuous drain current of 9.2A at 25C, and has a drain-source on-resistance of about 0.27 ohm. It is most often used as a low-side switch, letting a small control signal turn a larger DC load on and off.
Its gate threshold voltage is roughly 2V to 4V, so it begins conducting with a fairly low signal, but that 0.27 ohm on-resistance is only specified with 10V applied at the gate. Driven directly from a 5V or 3.3V microcontroller pin the device only partially turns on, so it works well for lighter loads or for setups where a dedicated gate driver or a 10V rail provides full enhancement.
The three legs are Gate, Drain, and Source, and the metal tab is internally connected to the Drain. Like most power MOSFETs it contains an intrinsic body diode from Source to Drain, which conducts if the drain is pulled below the source.
IRF520 MOSFET pinout
| Pin | Function | Type |
|---|---|---|
S Source | Passive | Passive |
G Gate | Analog | Digital input |
D Drain | Passive | Passive |
Specifications
- Dimensions
- 4.5 × 4.5 × 3.5 mm
Verified from the Tinkered component library.
Circuit requirements
- Use it as a low-side switch: put the load between the positive supply and the Drain, tie the Source to ground, and drive the Gate with your control signal. The control ground and the load supply ground must be common.
- The rated 0.27 ohm on-resistance assumes 10V at the gate. A bare 5V logic pin only partially enhances the channel, which limits current and produces heat, so reserve direct-from-Arduino use for smaller loads or add a gate driver / 10V rail for full-current switching.
- Add a series gate resistor (around 100-220 ohm) to limit the inrush into the gate capacitance, and a pull-down resistor (around 10k ohm) from Gate to Source so the MOSFET stays off while the driving pin is floating during reset or power-up.
- For inductive loads such as motors, solenoids, and relay coils, fit a flyback diode across the load. The internal body diode protects the MOSFET itself, not the rest of the circuit.
- Keep the gate-to-source voltage within the +/-20V maximum rating.
- The TO-220 tab is electrically the Drain. If you bolt it to a heatsink, either keep that heatsink isolated or ensure it can safely sit at drain potential.
Common IRF520 MOSFET mistakes
Treating it as a true logic-level MOSFET
The low threshold voltage tempts people to drive it straight from a 5V pin and expect the full 9.2A. On-resistance is only rated at a 10V gate, so at 5V the channel is only partly on, the part heats up, and it cannot pass its rated current.
No gate pull-down resistor
A MOSFET gate is a capacitor. If the control pin floats (during reset, boot, or a disconnected wire) the gate can hold charge and leave the load in an undefined state. A 10k pull-down from Gate to Source keeps it firmly off.
Skipping the flyback diode on inductive loads
Switching a motor, solenoid, or relay coil generates a voltage spike that can exceed the 100V rating or damage nearby logic. Always add a flyback diode across the inductive load.
Confusing the pinout
With the printed label facing you and the legs pointing down, the pins are Gate, Drain, Source from left to right, and the tab is Drain. Swapping them, especially Gate and Source, leaves the device stuck off or shorts the load.
Running near rated current with no heatsink
A bare TO-220 in still air can only dissipate a few watts. The 60W figure and the 9.2A current assume a proper heatsink, so plan cooling for anything beyond light loads.
Popular IRF520 MOSFET projects
PWM brightness and motor speed control
Driving the gate with an analogWrite PWM signal to dim a 12V LED strip or vary the speed of a small DC motor, keeping high-current switching off the Arduino pins.
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Build with the IRF520 MOSFET.
Drop the IRF520 MOSFET into a circuit, write firmware, and simulate it in your browser, then deploy to real hardware. All in one editable Tinkered project.