Recently Kemet supplied us with a new Tech Topic on VCC title Capacitance Change vs Voltage in Ceramic Capacitors. Below you will find a short summary of the papers.
*What is VCC?
VCC or Voltage Coefficient of Capacitance is a decrease in capacitance under applied DC voltages that happens in in ClassII and Class III MLCCs. VCC is often noticed while operating close to the rated voltage of the MLCC or where high capacitance is needed in the circuit. VCC is a result of the contruction of the MLCC.
Factors that influence VCC
- Applied Voltage : As voltage increase the capacitance loss in the capacitor also increases.
- Dielectric Material: Class II and ClassIII MLCCS formulation differences can have a significant impact on VCC.
- Design : Differences in dielectric thicnesses can have an effect on the electric field and can affect VCC differently.
What about Class I MLCCs?
Class one MLCCS are made from CaZrO3 and are very stable compared to ClassII or III which are made from BaTiO3. As a result they have almost no capacitance shift with AC or DC voltage.
Looking for more information?
See the complete Kemet document Kemet VCC PDF.pdf (438.3 KB) . Kemet also has an excellent article on What makes MLCC Dielectrics Different in their Engineering Center.