[Al (astral highway)]

The square pulse was set at 150uS. This is also the time between the displayed vertical rising edge and the end of the ramped waveform before the decaying sinusoidal wave at the end. In other words, the entire up, down, up, down up, part of the waveform before the decaying sinus wave is 150uS.

The circuit is pretty complex, with quite a lot of logic on board, and beyond the scope of this thread, but it and its layout are beyond any suspicion. It will rely on current feedback in its final application but is being switched by an external signal for the time being.

I can't measure the unloaded primary waveform without destroying the driver IC's.

What can you say about the circuit without reference to the circuit, only as it likely relates to the magnetising/ changes in magnetic flux in the ferrite and the generic causes of these sorts of behaviours and spurious waveforms?

Kalee/Peter - Cross post!

Ah, thanks for calling out that misnomer. 'Shock-excited ringing,' it is, then. That part of the waveform doesn't bother me so much as the ups and downs of the rest of it.

If you're able to share any hunches about the dereliction of the waveform without looking at the circuit specifics, what would you say? Assume a conventional gate driving topology with two well-decoupled gate driver IC's with plenty of oomph behind them.