Arlo1, I missed it somewhere in the conversation, but why don't you want to use the TO-220 based D44VH10/ D45VH10 transistors?
Below are two scope shots I took verifying my boost stage on my TD350E gate driver can actually deliver the claimed 15A it was designed for. The purple trace (math function) is the current in amps. You can see it delivered 14.4A in 570nS into a 1.0uF capacitor acting as my MOSFET stand in. Not sure what a 1.0uF translates to in nC. While this is not a test on an actual MOSFET that has Cgd and Cgs creating a Miller effect it does give some idea of the boost stage transistors performance. At lower current values the dI/dT increased and the over all current dropped down a bit, I think into the 12-13A range at 0.5uF hard to recall. The boost stage was fed by two 10uF XR7 caps in parallel. Gate drive power supply was 15V, 1W, so max of 68mA. It wasn't very happy supplying this current level at 19khz so I just did some single pulse tests. Only reason I have these scope shots is I decided to play around on the bench and verify some things + get some quality learning time in. That hour was VERY educational. Driver IC is a TD350E.
purple line is Amps
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Here is a picture of one of the gate driver setups that was used in the test. As you can probably guess, 3 parallel IRFP4568 MOSFETs don't need a boost stage to switch at 20khz, but I included them in my design anyways so I can verify the driver design real world.
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