Hello all,
I do have some outputs on a project where I use N channel MOSFETS activated by a digital output pin.
The mosfet can drive a 12V solenoid. What may happen is that if for any reason the output gets 12V (like shorted solenoid) the MOSFET gets destroyed.
What is the best way to protect the MOSFET from such a condition?
Thank you!
Don't forget the protective diode parallel to the selenoid 
I think in this case the presence of the MOSFET doesn't change or offer ways around the root issue, which is overcurrent. So a fuse or a PTC would be simplest solution, like in standard overcurrent protection.
Next step up might be a current limiting circuit, or a constant current driver. The current limiting circuit can re-use your MOSFET as the series impedance device, and the constant current driver could use the MOSFET as the linear element, so at least it's not wasted. But both will take some design effort. Will a fuse do?
I would measure the solenoid with an ohmmeter to see if it is shorted before connecting it to my circuit.
You could add a fuse 
Thank you for your answers! Going forward, I saw that in my project there is also another need but a similar problem. I need to trigger a relay which has 12v on one side and needs a ground on the other. However, instead of the relay pin being unconnected it has 12V on this side as well. So when the mosfet is ON to trigger the relay it gets burned or the output pcb trace gets burned. How could I protect the mosfet output since there will always be 12V on this contact? A fuse is not an option, could a zender do the job?
The gate circuit is not a good design practice with micro processors as the resistors as shown form a voltage divider reducing gate drive for the MOSFET. Move the pull down resistor to the port pin of the microprocessor. Also use an Avalanche rated logic level MOSFET, it will save a lot of grief in the future.
You could also use a smart low side driver that will provide you the feedback and shut down to protect itself.
A fuse is probably your best bet to protect against short circuits or excess current. But it isn't foolproof and there's an old joke..... "The transistor blew to protect the fuse." Sometimes that happens but In reality, if the transistor or MOSFET blows first, it usually becomes shorted so then the fuse blows too and that cuts-off power to prevent a fire or further damage.
But first, with inductive loads (motors or solenoids or anything with a coil) you should add a flyback diode like this circuit.
When power to an inductor is suddenly removed the magnetic field collapses, turning the coil into a generator that can generate hundreds or thousands of volts! And that can kill the MOSFET (or other electronics). It's the same principal used in your car to generate thousands of volts for your spark plugs from a 12V battery. A fuse will NOT protect against that. Fuses are for current, not voltage.
Other than that voltage is rarely an issue with 12 or 24V systems... Almost any MOSFET or transistor can handle 24V.
MOSFETS and transistors are usually killed by excess internal heat caused by excess current. That can happen very quickly, sometimes faster than a fuse can blow. Or, if the device is operated in the "linear range" where it's partially-on, it will have voltage across it and current through it at the same time. That generates lots of internal heat and you burn-up the device without exceeding the maximum voltage or current limits, but by exceeding the "safe operating area".
Hi,
Have you looked at specific solenoid drivers?
Google;
automotive solenoid driver IC
You are describing a situation that can occur in automotive electronics, they eventually use a fuse, but some drivers have current control and fault detection circuitry.
Tom.. 
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