7.4 Common Mistakes in Boost-Buck Circuits

Boost-buck circuits operate with both inductors in continuous conduction mode. Hence the inductor should be chosen with a value higher than that calculated, to allow for tolerances and for saturation effects (the inductance falls with increasing current). Calculate the value, add 20%, and then pick the next highest standard value.

Current ratings of inductors are given for a certain temperature rise in the core, typically 40 C. So if temperature rise is an issue, pick a component with a higher current rating.