Switching Power Supplies A - Z

Conduction and Switching Losses

Applying the Switching Loss Analysis to Switching Topologies

Now we try to understand how our preceding analysis pertains to an actual switching

regulator application — in particular, what “Vin” and “Io” are, with respect to the topology.

For a buck, we know that at turn-on, the instantaneous switch (and inductor) current is

I

O

× (1 − r/2), where r is the current ripple ratio, and “I

O

” is the load current of the dc-dc

converter. At turn-off, the current is I

O

× (1 + r/2). Usually, we can ignore the current ripple

ratio and take the current as I

O

for both the turn-on and the turn-off analysis. So the load

current of the