I haven't studied your circuit closely but I did notice that you are missing a resistor from base to emitter of Q16. Adding the resistor will help getting Q16 to turn off faster.

 

I haven't studied your circuit closely but I did notice that you are missing a resistor from base to emitter of Q16. Adding the resistor will help getting Q16 to turn off faster.

Yes you are correct. Initially I had a 100Ω connected there, but I did not notice any changes so I removed it. I guess when Q14 turns on, It pulls down so fast that it doesnt matter if Q16 is a little slow to turn off, but you are right, I should put it back in just in case

Thanks

 

A reminder. Don't forget to change the MOS-FET's to ones with higher gate threshold voltages. I misspoke in an earlier post and I now think that the Vth should be about 2.5 volts. With the parts you have, simulation shows peak drain currents of 45 amps! This is caused by "shoot through" when both FET's are on at the same time.

I chose FDS8962C_P for the P-channel and IRLML0040 for the N-channel from the parts available in LTspice. The peak current is now more like 5 amps. Note that I chose these parts quickly and I have not looked at their spec's so I would not use them in a real circuit.

One curiosity is that the peak current is higher in the second pair of FET's -- the ones driven by the first pair. I suspect that the risetime on the output of the first pair of FET's driving the load and the second pair of FET's is slower than the risetime they are driven with.