Multi-layer ceramic chip (MLCC) capacitors are used quite often in dc-dc converter input and output filters. They have low ESR, low ESL, and low cost. They also have no major reliability problems associated with them. All these properties make them suitable for power management applications. There are still, however, some issues to consider when using these capacitors in dc-dc converter circuits. Some ceramic capacitors can lose a lot of their value under certain conditions. This lost capacitance can degrade the transient response of a dc-dc converter, or it can even make the control loop of the converter unstable.

The capacitance per unit volume of the X7R/X5R dielectrics has increased quite a bit in the past few years. However, you should be careful about using the components with the highest capacitance densities. These capacitors lose a lot of their value at the higher frequencies where most dc-dc converter circuits operate. They lose even more capacitance when dc bias is applied to them.

Kingtronics specializes in application specific multilayer ceramic capacitors. Our product offerings included surface mount capacitors from the 0402 case size to larger high voltage units (up to 4KV) for Commercial and High Reliability applications.