arduino + mosfet

Hello, I’m trying to make a small size electronic switch 12v 2A max. I bought some fds6679AZ (-13A max) but I can’t find any schematic to make it work with arduino. I need to make it really small that’s why I need to use smd.

Could somebody help me please to find the good resistor value?

Many thanks in advance.

Search for “mosfet as a switch” and you will find examples. Look carefully at the difference between P-channel and N-Channel mosfets.
You can achieve what you want with the P-channel mosfet you have but will need an additional transistor or mosfet to drive the gate. With a Logic level N-channel mosfet you can make a pretty simple switch with two resistors and the mosfet.

Here is an example schematic showing both.
mosfetswitches.png

Hello, thanks for you answer, I will follow your advices and will use N channel.

Here is my schematic. I will use MTD10N50.

Cheers.

mini-motor-with-mosfet_bb.jpg

I would include the resistor in series with the gate as well though. This will limit the current from and to the arduino pin. without it you will momentarily draw more current ( or sink it) than the pin is rated for.

The gate of a mosfet acts like a capacitor, when the gate is turned on it will draw a large current. The resistor keeps this below limits for the arduino. To keep it under 30 ma ( safe limit) . The resistor should be 166 Ohms or larger. Anything between 166-300 should be ok.

I can't find a datasheet for that mosfet, are you sure that's the correct part number?

You mean like that?

Here is the datasheet:

mosfet_ar.jpg

That's the resistor but you still need the other resistor too!

That mosfet MTD10N05E is not a "logic level mosfet". It is intended to be driven by a higher gate voltage.

Two resistors -- (330 in my schematic) gate resistor to protect arduino pin (so nothing gets damaged from overcurrent). -- (10k) pulldown resistor to prevent gate from turning on when arduino is powering up and booting and arduino pin is in what called tri-state, neither high nor low. Otherwise what commonly happens is the motor will spin full power for a brief period on bootup.

Look for another mosfet.. look specifically for logic level mosfets, That means the gate can be driven by 5 volts or less. "Standard" mosfets are designed for gate potential of 10-15 volts.

Here is a suitable mosfet. http://www.irf.com/product-info/datasheets/data/irlr7843.pdf

Thanks for your advices, I now understand why the 10k resistor is so important!