For bipolar transistors, a large base current is required to maintain low on-voltage. However, since the MOSFET is a voltage control element, it can drive with small power sufficient to charge the gate. But because the input capacitance (Ciss) of the power MOSFET is rather large for high-speed switching, it is necessary to quickly charge the input capacitance with a low-impedance drive circuit.
For an indication of the gate current required for charging, it is possible to calculate the drive current simply by using the Qg characteristic prescribed on the data sheet. The required switching time is “t (desired)” (for example ton or toff), which becomes the following expression.
Electrical Characteristics: Power MOSFET Application Notes (PDF:1,092KB)