Over the years, ceramic capacitors have been used interchangeably with tantalum in many applications, class II ceramics being the one electrostatic technology that can achieve the high capacitance values typically associated with electrolytic capacitors. But because of MLCC shortages, we are currently at a point where designers are reconsidering electrolytic capacitors for applications that had switched to class II ceramic in recent years.
However, migrating circuit designs from MLCCs to tantalum electrolytics requires an understanding of multiple issues that impact how these different styles of capacitors will perform in the intended application. This article discusses the key parameters that differentiate these two capacitor categories in the various roles they play in power supply applications (bypassing, filtering, decoupling, bulk hold up and pulse power). It not only describes the range of parametric values, characteristics and options associated with MLCCs and tantalum electrolytics, but also the underlying differences in device construction and material properties that account for the differences in device performance and capabilities.
The discussion on electrolytics covers both tantalum and niobium oxide types and differences in these two material systems are explained. In addition to explanations of device physics and chemistry, details are provided here on capacitor packaging formats and capacitor modeling. All of this information is intended to help designers assess the viability of electrolytic capacitors as replacements for MLCCs in power supply and other high-capacitance applications.