As a first approximation, driving a MOSFET's gate means driving into a big capacitance.? The bigger/stronger the FET, the bigger is that capacitance.? It can be quite large, and part of it is from gate to drain where it may be multiplied by Miller effect.
?
Driving capacitance gives you (as a first approximation) an RC low-pass filter, meaning that the MOSFET's gate voltage rises or falls much more slowly than the nominal rise and fall times of the driving device if it had no load.
?
Hopefully you take that into account.? That is where those MOSFET gate drivers help.
?
Andy
?
