Following this question, I ended up with the following diagram to drive a custom made dc motor using Arduino (omitting the 5V and 12V power supply stages which work properly): I keep burning instantly the irfp054n mosfet. An by instantly, I mean it. I tested with a voltmeter the voltage output by the Arduino PWM pin 5 and it's between 0 and 5V. The voltage coming out from the TC4422 (pins 6 and 7) is between 0 and 12V. Right after giving power to the whole system, I see the motor running at full speed, so I turn off the power and measure a resistance of about 0.2 Ohm between drain and source on the mosfet, which means it's gone. What am I doing wrong? Any hints?
UPDATE: Ok, ok, I'll get rid of that diode... Anyway, I installed it right after burning the first mosfet so I wouln't think it's the cause. Just out of curiosity: could it be that the problem comes because the Schottky and the mosfet are screwed on the very same aluminium heatsink?
UPDATE: It works, I replaced the diode between driver and mosfet with a 120 Ohm resistor and the mosfet is now a much stronger IRFB4115Pbf. I still have some glitches to work out: when I shut down the 5 V and 12V circuit, the motor runs up to full speed. Any ideas?