Selecting inductor and capacitor values for tracking preregulator?

[conducteur]

In a tracking-preregulator (buck converter), how do you calculate the values for the inductor, output capacitor and flyback diode? Do you use maximum current and maximum voltage difference in vs. output?

[MagicSmoker]

If the buck has to deliver a wide output voltage range as a preregulator then the L, C and FWD component values will necessarily be a compromise. The worst case for the inductor and capacitor are when Vo = 0.5 * Vin; the worst case current rating for the FWD occurs when Vo is at a minimum (typically 2V - 4V higher than the output voltage of the post-regulator).