This is the real reason for using an NPN to drive the MOSFET.And the circuit with the transistor is used when the V1 supply is above the micro supply.
We tend to see quite a few posts here where folk try to drive the FET directly with higher V1 volts and that will not work.
The FET will be on all the time and the port will probably be popped.
by Aaron Carman
by Jake Hertz
by Duane Benson
by Jake Hertz