Re: Help with IR2112/3
1. The driver circuit dimensionioning hasn't to do with output rating rather than gate currents. High power tranistors haver usually larger gate capacitance and possibly use higher gate currents (depends also on the intended switching speed).
2. It's a threshold voltage, the gate driver supply must be considerably higher than it. 15 V is O.K for any standard IGBT or MOSFET.
3. It's O.K. to chosse the same value, but it's less critical than the bootstrap cap.