Hello,
I would just like to verify, if my sketch is OK and if this would work? Is the zener diode oriented correctly and is it suitable for this MOSFET? It is an IRL540N, exactly like the sketch?
Thank you for the feedback!
Why do you think a zener diode is needed.
Study this page.
Leo..
Nice page. But series RC instead flyback diode is missing there.
Because it fried the MOSFET without it. So I have to include it. I am not sure if it is suitable one or if the orientation is correct?
What would the sunbber be needed for if I have the zener diode?
Hi, read the page. It is not a zener diode. It is regular pn or Schottky diode, called flyback diode, because is shorting the current, generated by the coil when the field collapse.
An RC instead a diode can also be used in some cases, but this is another subject.
So what would be a perfet solution in this case? I need a 6.8 - 12 V zener diode i think? But does it connect the way I did in the schematic?
What is driving the MOSFET Gate? If it is Arduino probably no Zener is needed.
What is the coil?
I would try to decrease R1 to 100 Ohm or even less to decrease switching losses in the MOSFET.
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It is a IRL540N, so it can be directly driven by arduino output.
The coil is a Push/pull solenoid, 1,55 Ohm coil, so at 24 VDC ot draws 15 Amps!
That is a lot, so i need to figure out a way to make this work, as with just the circuit provided (without a zener diode), the MOSFET died with first try driving the load 
Needles to say I had a big heat sink attached
Hi, @xcg584
Can you please post some images of your project, so we can see your component layout?
Please check ALL your gnd connections.
Thanks.. Tom.. 
You probably need a heatsink at 15A. Maybe a big one... It heats-up when current goes through it, and the hotter it gets the less current it can take.
There is a chart on the datasheet showing case temperature vs current.
Will provide tomorrow, it is now late where I am.
About the heat sink, I mounted the IRL540N on a big old PC processor heatsink, and after the test, where the MOSFET blew, the heatsink was still cold so i assume not that much heat dissipated
What voltage is applied to the MOSFET gate (point D) on your diagram? You should have a kickback diode rated at least 10 Amps.
Which Arduino, 5V or 3.3V?
Internal temp is important, not the temp of the heatsink.
Did you mount it properly, with thermal paste.
At 15A, the transistor dissipates 17.3watt. Quite a lot for a TO-220 case.
Did you use PWM, and at what frequency. PWM adds switching losses (heat).
As JCA34F said, the diode must match the load. More so if PWM is used (use a Schottky diode).
Two fets in parallel could be a solution.
Leo..
You made some really serious wiring mistake. The IRL540 gate cannot possibly be destroyed by an Arduino logic output.
Don't even think of building this circuit on a breadboard. The tracks will burn, creating unpredictable havoc.
The circuit looks OK but I do not agree with your component choice. Your flyback diode, 1A, needs to support the coil current, 15A. If you used a Vishay MOSFET the internal avalanche will support a 28A pulse at a 1% duty cycle. It should be OK if you are not doing PWM. The gate resistor should be in the 50 Ohm range to keep the circuit solid and hopefully oscillation free. Your zener will be just fine and will help save the MOSFET if you have long wires on the circuit.
You will get about a 1V drop across the MOSFET giving you about 18 Watts of heat. The TO220 will rise about 62C per watt. Your heatsink needs to make up the difference. For these currents you need heavy wire. Best to make a circuit board with the appropriate trace size or solder heavy wire to the drain and source leads.
Hi,
We eagerly await some images of your project.
Tom..
Added pictures of the real thing.. .
jremington...I am sure the MOSFET wasn´t fried from the arduino output, but from the inductive load
gilshultz...The solneoid isn´t beeing driven by a PWM signal, just a normal digital ON/OFF logic..
So i should mention, the solenoid flyback diode is a 1N4007. Is it too small (the current I mean). It does have a 30A peak current so it should be ok?
Tom...So the picture with the whole thing assemled. There is the solenoid (diode is soldered directly to the solenoid pins), powered with a powerfull power supply providing 18V, the negative solenoid terminal goes to the heatsink and MOSFET via screw. As the drain on the mosfet is the middle pin and the top part..The blue wire is the digital ON/OFF signal from arduino, and all three GND´s (Arduino, power supply, and from MOSFET) are connected together with wago....I am clueless why this doesn´t work...
It looks to me as though you have at least 2m of wire between the Arduino and the MOSFET.
That's going to pick up a large voltage spike as the solenoid gets switched.
There is going to be a voltage drop across that 3m(?) of black wire due to the high current flowing through it.
That means that the source is going to be at a higher voltage than the Arduino GND pin, thus reducing the gate voltage.
I don't see the diode across the solenoid coil - where is it physically located?
Hi,
Hard to see, have you got the UNO gnd connected to the solenoid power supply gnd?
Thanks.. Tom..