It is not always necessary to perform these calculations since KEMET’s KSIM tool provides both the AC voltage and current across a wide frequency range. This allows designers to simulate MLCCs in both the voltage and current limited regions to determine maximum allowable AC voltage and maximum allowable AC current. In this example, a KC LINK 100nF, 650V part is being simulated from 10kHz to 1MHz providing both the maximum allowable AC voltage and maximum allowable AC current across the entire frequency range. Since this is a 650V rated MLCC, the maximum RMS voltage using the voltage rule is 650 divided by 2 times the square root 2 which is 230V_RMS. Shown on the graph, below roughly 65kHz, the maximum allowable voltage is 230V since there is not enough AC current to generate excessive self-heating. This is the voltage limited region of the voltage and current plot. Note that as frequency increases from 10kHz to roughly 65kHz, the AC current is also increasing and thus so is the MLCC heating due to I²R losses. After roughly 65kHz, the MLCCs temperature rise tries to increase above its safe zone temperature of 20°C. However, KEMET’s KSIM tool limits the AC voltage and current so that the temperature never exceeds the safe zone. This is the current limited region of the voltage and current plot.