I'm following the instructions for external gate resistor selection (SLLA385A), and the app note describes a process where oscillations at the gate of the FET are probed to characterize unwanted ringing.
The app note does not say whether this measurement is to be done with the FET loaded with your typical load, or unloaded.
I am currently taking measurements and finding that the ringing is certainly different depending on whether or not the FET is loaded. Ringing is generally worse unloaded (easier to measure!).
How should this measurement be done?
Furthermore, the app note mentions that the gate driver output resistance Rhi and Rlo play a role and are to be considered in calculations as well, but I'm not sure what this would be. Rdson of the gate driver output stage devices?
Even the gate driver used in the app note, UCC5310MC, does not appear to specify any output resistance in its datasheet. What should be used here?