The selection of the output inductor is one
of the most important choices to make in designing a converter. The following is a short
list of considerations to make when determining the value of the inductance used. Other
considerations are found in the Section 7.
Start with an inductor value that
results in a ripple current (ΔI) between 30% and 50% of full load.
Equation 4.
- A choice of inductor value has a direct
correlation to load transient response. Too large an inductor value can result in poor
load transient response.
- The ripple current has an impact on the
DC load current at which the converter enters current limit. Make sure that the peak valley
current at full load is less than the current limit threshold by an adequate margin. A
recommended range is 60% to 80% of the current limit threshold.
- The ripple current has an impact on the
RMS losses of the converter. The higher the ripple current, the higher the RMS
losses.