Yeah, that's not gonna work. You would need two separate floating 12 V PSU or a high side bootstrap driver.
I see that is taken directly from a TI application example. Maybe I am mistaken but I cannot see how it can work.
Sorry, didn't pay enough attention. It IS a bootstrap. And It says it right there. I wasn't paying attention.
Well, It should work.
I would test it with no load and with the PSUs current seriously limited so it will not blow anything up. Check that you are getting the on and off times right and very especially that both are not on simultaneously as that would cause shoot-through from the 40 V PSU.
I have not studied the IC in detail. Are you absolutely certain it cannot enable both transistors at the same time? Because that would short circuit the 40 V PSU.
What PSU was overloaded?
Do you understand well how it is supposed to work?
I designed and built a very similar circuit but with gates so it was foolproof. Look at the waveforms. It is crucial that you have dead time between one switching off and the other switching on or you will have shoot through.