Using MP8880 with Inductive Loads

DC-DC Power Converters
1

We’re looking at using the MP8880 in an application where it can be exposed to some inductive loads. When testing shutdown transients with the EV8880-V-00A and reference loads we’re noticing the flyback appears to be conducting through the body diode of the low side FET before conducting though the flyback diode we’ve added to the EVM board. We are shutting down the load using the enable pin of the MP8880. Do you have any recommendations to protect the MP8880 from the flyback?

Admittedly, I’m using a diode from my snack drawer… not the nicest low voltage Schottky. Is there a forward voltage of a flyback diode that would guarantee we flow the flyback current through the flyback diode?

Interested if you have other solutions or recommendations as well, perhaps we can manipulate the output voltage setpoint digitally?

2

The power converter always operates into an inductive load, see that inductor there hooked up to the SW pin? It is a synchronous converter, which means in parallel with the catch diode it has a FET that is turned ON during the normal switching cycle to conduct flyback current with lower loss than a diode would have. If you worry about it, hook a nice big schottky across the output to carry the inductive kick from the load and forget about it. How big is this inductance?