Hi,
I need to step down 400v dc to 300v, with minimum energy losses.I'v suppose an buck converter will be good solution. I need help on how to drive power-Mosfet with pwm controler like SG3525. Because the sourse iz on high potential , and i think the gate have to be isolated from the ground to.
So this is non isolated buck converter, for 300v/1A power, from 400v in.

Thank you