so i have a pFET, IRF9Z34N, Vsource = 5v, and a DIO pin that goes 0v and 3v. the pFET has a threshold voltage of Vgs = -2 to -4v, and an input capacitance of 620 pF. will the pFET turn all the way off at 3V? and should i have a pullup between the source and gate? (the DIO is a 5v tolerant pin). i need to switch it on and off at 500kHz.