Now with the gap shorted there should be no voltage induced at the lower switch the moment the boost converter switch flips, as the lower one has much lower R_on anyways. And when the lower switch closes not much should be induced as the energy in the inductor is now transferred into a 10 times larger cap.
>picrel
well nuh uhh
What is that? The timing if the spike coincides with the upper switch timing. It is much earlier / faster than the SRF of the LC thing allows for, so arrives earlier than the usual spike would.
It doesn't look like the usual measurement artifacts but I hope it is and I can't explain it otherwise.
To the very left we see the boost converter switch coming on and killing the very slow spike that was induced by switching off the lower switch.
Odd huh? 100V is too close for comfort for the lower switch.
Increasing charge time for the boost converter seems not to have an effect this spike is always ~ 100V so glitch?