Mosfet Power Source Switching

This is a problem that was continued off of the thread here: http://forum.arduino.cc/index.php?topic=166074.0 This is a (new?) problem and i really need help

So I had my low side power switch working the other day... or so i thought. Turned on the robot, and instantly the FET started smoking, I haven't touched anything, just turned it on and BAM. Smoke I burned my hand disconnecting it. No solder bridges, no arcs, nothing. I am literally at my wit's end

Well, you had a lot of wiring mishaps.

The FET’s tab (heatsink) is Drain, too.

Dwg attached.
You have to wire it right the first time.

FETproj.JPG

I'll wire it up, but I don't see any mishaps, I see a protection diode (which I don't remember being critical) and a resistor which also doesn't seem to matter as the FET's input is... damn 2.5 volts.... WAIT the thing starts up even if only the input is connected... even if the MCU is off, the thing turns on when it is connected to a wire.

I have nothing connected to the Tab either

The circuit still works to turn a LED on and off, so a resistor must not be critical(famous last {unintelligent} words)

It's a FQP30N06L, see any problems with my post so far?

SilentDemon555: I'll wire it up, but I don't see any mishaps, I see a protection diode (which I don't remember being critical) and a resistor which also doesn't seem to matter as the FET's input is... damn 2.5 volts.... WAIT the thing starts up even if only the input is connected... even if the MCU is off, the thing turns on when it is connected to a wire.

Then you have missed out the 10K resistor. Its purpose is to ensure that the gate is at 0V when the Arduino is not connected, or is connected but has not yet set the mode of the pin that drives the mosfet.

SilentDemon555: So I had my low side power switch working the other day... or so i thought. Turned on the robot, and instantly the FET started smoking, I haven't touched anything, just turned it on and BAM. Smoke I burned my hand disconnecting it. No solder bridges, no arcs, nothing. I am literally at my wit's end

Do you have a pulldown resistor on the gate?

Oh no, I thought I said that. Yes I have a 10k resistor from gate to source

That's a 60V MOSFET, what supply voltage was used?

The switch is a low side, so it's connected to the common ground of a 6v, 1.6MAH rechargeable pack. As I was told, the 60v means absolute max, so says on the fact sheet

SilentDemon555: I'll wire it up, but I don't see any mishaps, I see a protection diode (which I don't remember being critical) and a resistor which also doesn't seem to matter as the FET's input is... damn 2.5 volts....

In the other Subject that you linked (and I think this should have stayed there), there were posts about mix-ups, things just starting to work all of a sudden, and so on.

I was just trying to be diplomatic.

As far as the diode there goes, I figured since it's a servo controller that there might be "some inductance" involved. I didn't include any redundant or unnecessary components. I think what I showed is exactly what's needed, placed exactly as it all ought. From there, it's all a matter of managing spatial relations and following instructions.

SilentDemon555: The switch is a low side, so it's connected to the common ground of a 6v, 1.6MAH rechargeable pack. As I was told, the 60v means absolute max, so says on the fact sheet

OK, plenty of headroom on the voltage spec then ;)

I split the thread and sent it here because the other one seemed to die. I followed directions, I checked for bridges, There was nothing wrong with it... It worked then smoke Ugh I'm still waiting for parts so...

SilentDemon555: I split the thread and sent it here because the other one seemed to die. I followed directions, I checked for bridges, There was nothing wrong with it...

The last Reply to that Subject was made by you:

I fixed the problem I guess. I have no idea what happened, I tried it every which way and even ways I knew wouldn't work. I had grounded the MCU to the wrong pin of the MOSFET, the MCU has to be wired to the non-load side of the FET, not the middle pin but the far right.

I swear I tried this already, but I guess life just hates me haha"

which clearly explains, at least to me, why it "seemed to die."

Now, if you think that what I have shown you (see Reply #1) is anything at all like what you've done [ http://forum.arduino.cc/index.php?topic=166074.msg1241450#msg1241450 ] then you're not paying attention.