Hi, I am trying to make a buck preregulator based on a TL494. The unregulated input voltage is between 70 to 80v. Represented by V1 in the schematic. The TL494 ground will be at vun and it is represented by V3 its Vcc will be 16v referenced to vun. The PWM will drive Q3 (Vceo >100v). (Or perhaps a nmos). Q1 and Q2 are 2n2222 and 2n2907.
The only way that I found to clamp the voltage at the collector of Q3 is by the diode D. Is there a better way to do it?
I cannot use a dedicated gate driver IC
Simulation seems to work. Of course I will recalculate all the resistors (their values are just for for the sim)
I included a 15v zener between Gate and source of the pmos.
Thanks for any help