Whilst looking at the possible parts for a boost converter I came across references to making sure that the capacitor could handle the "ripple current". I looked a bit further and can see 2 possibilities. 1) The ripple in the capacitor current itself ie the difference between the minimum and maximum capacitor current. 2) The other possibility is that there is a ripple current called delta i,L which is mainly affected by the size of the inductor for given input voltage and duty cycle. I found a capacitor which lists its "ripple current" rating as 0.8A/800 mA. Does this mean it can handle a ripple of 0.8A in the inductor current or can its own current only vary by +/- 0.8A? The source of my confusion may be misunderstanding a page here - http://www.analog.com/library/analogdialogue/archives/45-09/boost.html "The current ripple, shown as ΔIL ...The average inductor current flows into the load, while the ripple current flows into the output capacitor"