Technical Article: Surface Mount Capacitors for DC-DC Converter Applications

Surface Mount Capacitors for DC-DC Converter Applications
Written By: Naotaka Hata
Tantalum, polymer, ceramic, film, and aluminum capacitors each offer a different set of operating and performance characteristics. Choosing the proper capacitor when designing DC-DC converters requires a careful understanding of these differences. High voltage front-end connections to the power source typically rely on aluminum capacitors, while intermediate step-down voltages often look towards the tantalum and ceramic families to take advantage of volumetric efficiency. The final load decoupling and bypass capacitors are generally found in the ceramic and film families.

Surface mount (SMD) capacitors can be constructed using several different technologies to achieve a range of voltage tolerance, bulk capacitance, and parasitic device characteristics. As shown in Figure 1, these technologies can be roughly broken down between ceramic, film, tantalum electrolytic, and aluminum electrolytic with varying degrees of application overlap.