Scenarios for this current rating on MOSFET drivers

[kelvne]

 Trying to delete my account [ Specified attachment is not available ]

[langwadt]

if you want to switch a (big) fet on/off fast you need a lot of current to charge/discharge the gate capacitance

[srb1954]

And the effective input capacitance at the gate is increased by the Miller effect boosting the effect of the gate-drain capacitance. This Miller effect capacitance can be greater than the static gate-source capacitance thus requiring even more drive current to switch the FET rapidly.

A good description of this can be found in the Unitrode application note U-137.

[Nominal Animal]

And do not forget: the current is only supplied as a short pulse, not continuously.

Essentially, the charge \$Q\$ transferred to the gate is an integral of the current with respect to time.  The faster you want to completely switch the MOSFET state, the higher the instantaneous current has to be during the pulse.