I used this circuit to complete my KhudaydusUno 32 bit MicroController board
thus I could protect any accedent shorting between +3.3V & +5V ports. Thus preventing any damage may occurs on PIC32 Chip (supplied with+3.3V)
An external voltage regulator for Arduinos and stand alone ATmega328P micro controllers. Offers reverse voltage, over votage, and over current protection. Output voltage is adjustable via a potentiometer.