Switching Power Supplies A - Z

Chapter 2

In general, for most practical purposes, the current rating of the inductor that we need to

consider is the lowest rating of all the published current ratings. We can usually simply ignore

all the rest.

There are some subtle considerations and exceptions to the argument for always preferring

an inductor with I

DC

≈ I

SAT

. For example, under transient/temporary conditions, the

momentary current may exceed the normal steady operating current by a wide margin. So for

example, suppose we are we using a switcher with an internally fixed current limit ‘I

CLIM

’of

5A—ina 3-A application. Then under startup (or sudden line/load steps), the current is

very ...