Min capacitance equation for swithcing reg contains both L and uH?

[Starlord]

http://www.ti.com/lit/ds/symlink/tps61202.pdf

On page 16, there is an equation:

Cout = 5 x L x uF/uH

First, what the heck is L here?  uH is the inductor's inductance.  Am I supposed to plug in the inductance twice?  Why use two different symbols for the same value in the same equation?

Second, what's uF?  It's not Cout because Cout is on the left side of the equation there.  And same question as above, if it's the same thing, why use two different variables?

Maybe Cout is in farads and L is in henries?  Why use L instead of H?  Because the schematic symbol for an inductor is L perhaps?  So L is equivalent to Cout; a label not a unit; and both are specified in whole units?

[Neilm]

The only thing I can think of is that it is to get the correct units for the capacitance.

[T3sl4co1l]

Unit conversion.  L is in uH so it has to be divided by a constant of 1uH to get rid of it; then C /is/ in uF so the expression has to be multiplied by 1uF.

H/F == ohm^2, so they could've used 1/ohm^2 just as well.

More particularly, they could've attached a number to that unit, which you will find is related to either the switching impedance (Vsw(pp) / Isw(pk)) or the source or load (Vin/Iin or Vout/Iout), all of which are at least in the same neighborhood.  Seemingly, they assume this is around 1; the 5 sounds like a "magic number", such as ripple% (of the inductor current, or output voltage, or their ratio).

Tim

[bson]

uF/uH is the unit, not a value.  If you multiply uF/uH * uH you get uF.