How would you know whether to trust your power supply? I am using higher end(?) PSUs
Would I want to add any additional protection?
Calculations are off:Rds = 0.042 at VGS = 4.5 V
Proper switchmode supplies include a "crowbar" circuit to short out and shut down the supply with a thyristor if there is an internal failure and the output voltage rises above a reasonable level. Not all however are properly engineered.