Hi,
I did design 24 to 330V boost and it worked. I see 330 V many times and output capacitors charged everything look good at output however, i see just one time, when i change LM3478 ic, circuit works againt but after 5 minutes, i cannot reach 330V. Every time i need to change ic. There is a fault i know but i couldnt found . Below my design,
With warmest regards.