The inductor must be selected such that the transient performance and ripple requirements are balanced for a particular design. In general, a smaller inductance increases loop bandwidth leading to better transient response at the expense of higher current and voltage ripple.

Determine the amount of inductor ripple current desired for the converter. 25% to 40% of the maximum DC output current results in a good compromise between RMS losses (in the MOSFETs and inductor) and good load transient response.

Now select an inductor capable of withstanding the DC current. A good selection

• Has inductance droop of less than 20% of initial value at full load
• Not saturate under overload conditions
• Has low DC and core losses at the frequency of operation
• Has a temperature rise within the bounds of the operating environment

In this example, a 120nH, 0.2-mΩ inductor is used.