If one was to design at the output a low-pass PI filter with a cutoff frequency of 10kHz for example (purely hypothetic), how would one proceed?
I don't see much information about the PI filter. Somewhat there is no real voltage Vo/Vi transfer function like a LCR filter, but instead there are design rules like using the line characteristic impedance \$Z_0\$ if I stand correct (like here).
I'm not even sure what to put as \$Z_0\$ because after all this would be on a PCB so the line impedance must be extremely low? Does it really even matter?
Except, with a SMPS IC it's next to impossible to determine the output resistance of the IC, or the equivalent load impedance \$Z_L\$ (imagine you design a PSU, there are tons of loads possible here, and nevertheless if you supply say a MCU you cannot really predict that load because it's variable).
So given all of this, how does one actually implement a PI filter to filter the ripple voltage, given your Q factor must be around 0.707 to avoid making an oscillator in the process? Given for example a max current of 100mA, fc=10kHz, \$Z_0\$=no idea (how would you determine it)?