Will one of you be so kind as to double check my circuit here? This is feeding voltage from a battery to a switching buck regulator that supplies 5V to my Arduino and a few other things. Maximum current is 3A so max I'm moving 15W. Really much less than that, but going with max ratings to leave a margin. It's gotta be high side because of the way the grounds are connected later. That much I have been schooled on already.
The pin feeding it is not an Arduino pin, it's from a port expander. It has a 20mA max current.
Max Vgs for this P-FET is -16V. My supply can be from 7 to 18 depending on which batteries are hooked up. With the 1K and 330 I should be able to go to about 21V before I hit the max Vgs. And at the low end of my battery I'll still have about -5.25Vgs which should be just enough to get it turned on. I think I'm well within tolerance on everything else.
Or at least that's my novice opinion. I'd appreciate anyone who knows a bit more.
This may not be the best transistor, but it's what I have on hand. If it will work it will beat buying something.