Something odd is happening in a h-bridge design I've made.
The part numbers in the picture are wrong, sorry. The n-channel mosfets (the bottom 3) are all 2N7002Ps, and the P-channel mosfets are BSS84CTs. Both have >40v rating, and are logic level. Also, the +5v tag is wrong, it's just a generic rail that I'm injecting power in from.
The bottom n-ch mosfet's gate runs down to an I/O on a microcontroller (to act like an enable), and the two main gate wires go to an inverter, so that neither of them are active at the same time, and so I can control this h-bridge using only 2 pins. This driver is just running a small ultrasonic transducer, so there's not much load at all.
Everything works well at 3.3v on the +5v. The transducer is powered normally, everything "functions within acceptable parameters" as Data would say. There is no heat emitted from any of the mosfets. Unfortunately, I need a higher voltage for my application. As soon as I put the voltage to 12v (still half of what I need), all the mosfets loose their smoke and glow quite nicely for a few seconds. Also, they invariably short their gates to +24v, which also seems to toast my $12 ARM micro on the board.
Any assistance to why the heck this is happening would be greatly appreciated.