P-Channel MOSFET high side switch in an MPPT buck converter gets very hot with no load
Based on the datasheet:
Remember virtually no DC current flows in or out of a MOSFET gate, so if gate resistor is 22 ohms to 100 ohms it is fine, high enough so Q3 / Q2 do not &quot;ring&quot; with ON/OFF transistions.
A large bypass capacitor is shown between Q3 and Q5 so the output has a stable current source, not affected by Q5 ON resistance.