So I did check the cap ripple equation and the bottom line is those numbers were actually too high. Basically what I scribbled down looks like equations 24 and 25 on page 6 here:
http://www.ti.com/lit/an/slva630a/slva630a.pdf (fixed the link)
For output ripple, really only the capacitive part ends up mattering, so what phase angle to add the resistive part in (which creates the other detail in that paper really) is irrelevant. The cap term is just Q/C where Q is average I*t and the rising time is haf of 1/f and the average current is half of the max current and the max current is half of the peak to peak, so with three halves you get v_p2p = 1/8 * I_p2p/(f*C) as per above link.
But the powerlectronics equation doesn’t really agree with that for a couple of reasons, which seem to me to just be wrong, and wrong usually actually too high. I’ll use equation 25 from Ti now which you can see still errs on the high side compared to their simulation.
Components:
Ok I looked at caps a little again. I’m sticking to my 1210 recommendation. There are no 10uF caps on digikey in x7r with ratings 35V or higher in anything smaller (and the 50V ones have the lowest ESR). Furthermore, I looked at larger caps and they get REALLY expensive in those kinds of specs:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=209394405
That’s a cheap one. The one’s in between cost twice as much.
and it’s not clear you can do any better. For output 10uF is enough. For input ESR is really the problem anyway and above 10uF the caps are pretty much all measured only at low frequency. Even for 10uF where they’re measured at 1khz, I’m not sure I trust extrapolation to 1Mhz well, but at least I can find some cheap ($.30)
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=209396138
and some individually specced (rare, reading through these cap sheets is a pain) up to high frequency, even if not amazingly low ESR (average).
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=209397082
I would recommend room for two or three in parallel on input though.
So I’m done with caps. If you can find something with more capacitance, less ESR, rated better for high frequency or in a smaller package, have at it, but this is the best I got. I am probably about done with diodes too once I post what I have, so a power Mosfet will wrap up the main bits.