Careful selection of inductors is necessary for automotive DC-DC converter applications to achieve the right combination of cost, quality, and electrical performance. This article provides guidance on how to calculate the required specifications and the possible trade-offs.
There are approximately 80 different electronic applications in automotive electronics, each requiring its own stable power rails derived from the battery voltage. This can be achieved with large, lossy "linear" regulators, but a more efficient approach is to use "buck" or "buck-boost" switching regulators, as they offer efficiency exceeding 90% and are more compact. This type of switching regulator requires an inductor, and selecting the right component can sometimes seem a bit mystical, as the necessary calculations are rooted in 19th-century theories of magnetism. Designers hope to see an equation they can "plug in" their performance parameters to obtain the "correct" inductance and current ratings so they can choose from parts catalogs.
However, things are not that simple: assumptions must be made, trade-offs must be considered, and multiple design iterations are often required. Even then, the perfect component may not be a standard feature because a redesign is needed to see if an off-the-shelf inductor is suitable.
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