Magic smoke escaped my Feather

Hoping somebody can help point out what I did wrong last night.

I have a Adafruit Feather M0 development board which I wanted to use to control a LED array. Because the array required a 9v supply I decided to use a seperate 9v battery and switch it using a MOSFET.

Becuase I'm basically lazy I purchased a IRF520 module from Amazon and wired it up as per the attached image.

I loaded the blink sketch up and set pin 14 (A0) as the output pin. Then uploaded the sketch onto the Feather.

At first all was working well but after a few minutes I noticed a glowing ember on the main chip and before I could react the magic smoke that makes all electronics work had escaped from my Feather.

Obviously the Feather is now fried and not much use to man nor beast.

At first I suspected that the problem may have been I mistakenly connected the 3.3v VCC of the feather to the VCC on the IRF520 module (as well as SIG and GND) but as far as I can tell the VCC on that module is not actually connected to anything so I'm at a loss as to what went wrong.

I have a new part on order but really can't afford to repeat the mistake. Can anybody help educate me please?

(mod edit)

Double check the printing on the module matches the pins. Not unheard of for the Chinese to get even the simplest things wroung :)

Have used MKR's to trigger some of those modules with no side effects.

Thanks Bob

I've done as you suggested and worked through all the connections with a multimeter. What I came up with was an exact match for...


Confirmed that the Vcc pin in on those modules is not connected to anything so that wasn't my problem.

Also confirmed the MOSFET is really a IFR520 so I know the legs are right.

Am now at a total loss as to what went wrong.

I really cannot see why it would have fried the feather based on what we can see. The IRL is actually a better choice as it runs at logic level.

IRF540 requires 10 volts Vgs to get .077ohms Rds IRL540 requires 5 volts Vgs to get .077ohms

I have swapped a couple of mine when I blew them up, just de-soldered the IRF and dropped in a logic variant. Also mounted heatsinks on a couple of them as sometimes I was getting close to a failure point but didn't want to swap it out.

Do you know if the mosfet also got hot ?

Thanks again.

It's nice to have confirmation I was approaching it right. Not sure if it got hot as I didn't test at the time. In theory the MOSFET should have easily been able to handle the current being thrown at it.

I am taking the recommendation and now have 10 IRL's on order I will try swapping out with the IRF's to see if it makes a difference.

Think I will setup a test rig to generate the 3.3v signal on a button press rather than risk another dev board just yet. That way I can investigate all the voltages etc.