Inverting Boost Converter that Short Circuits?

Thread Starter


Joined Jan 28, 2022

I have an inverting boost converter which is giving me some difficulty. It can be found on pages 1 and 3 of the PDF attached (the non inverting works fine). This inverting boost converter should (and has in prototype) produced -100V - 0V without any difficulty.

All control signals are fine and totally adjustable, I've tried a frequency from 10kHz all the way to 200kHz and various PWM duties and pulses. No matter what I do the best I can acheive is -20V WITH the the circuit riding my 400mA PSU current limit. I'm completley baffled as to what could be wrong.

The PWM pulses are generted from an IC with variable frequency and produce 5V at 20mA which should be plenty to drive the MOSFET driver. Any ideas would be much appreciated.

I have checked that the saftey circuit is not faulty and that the relay is coming on!

Thank you!