Ceramic Capacitors FAQ

Characteristics

What is the allowable Ripple current Murata's ceramic capacitors can withstand?

There is no allowable current (ripple) specification for ceramic capacitors, but you should carefully follow the points below, and confirm them in the actual circuit before use.


Confirm the operating conditions to make sure that no large current is flowing into the capacitor due to the continuous application of an AC voltage or pulse voltage.When a DC rated voltage product is used in an AC voltage circuit or a pulse voltage circuit, the AC current or pulse current will flow into the capacitor; therefore check the self-heating condition.Please confirm the surface temperature of the capacitor so that the temperature remains within the upper limits of the operating temperature, including the rise in temperature due to self-heating. When the capacitor is used with a high-frequency voltage or pulse voltage, heat may be generated by dielectric loss.


<Applicable to Rated Voltage of less than 100VDC>
The load should be contained to the level such that when measuring at atmospheric temperature of 25°C, the product's self-heating remains below 20°C and the surface temperature of the capacitor in the actual circuit remains within the maximum operating temperature.


<Applicable to Temperature Characteristics X7R (R7), X7T (D7) beyond Rated Voltage of 200VDC>
The load should be contained so that the self-heating of the capacitor body remains below 20°C, when measuring at an ambient temperature of 25°C. In addition, use a K thermocouple of ø0.1mm with less heat capacity when measuring, and measure in a condition where there is no effect from the radiant heat of other components or air flow caused by convection. Excessive generation of heat may cause deterioration of the characteristics and reliability of the capacitor. (Absolutely do not perform measurements while the cooling fan is operating, as an accurate measurement may not be performed.)


<Applicable to Temperature Characteristics U2J (7U), C0G (5C) beyond Rated Voltage of 200VDC>
Since the self-heating is low in the low loss series, the allowable power becomes extremely high ompared to the common X7R (R7) characteristics.However, when a load with self-heating of 20°C is applied at the rated voltage, the allowable power may be exceeded. When the capacitor is used in a high-frequency voltage circuit of 1kHz or more, the frequency of the applied voltage should be less than 500kHz sine wave (less than 100kHz for a product with rated voltage of DC3.15kV), to limit the voltage load so that the load remains within the derating shown in the following figure. 
In the case of non-sine wave, high-frequency components exceeding the fundamental frequency may be included. In such a case, please contact Murata. The excessive generation of heat may cause deterioration of the characteristics and reliability of the capacitor.(Absolutely do not perform measurements while the cooling fan is operating, as an accurate measurement may not be performed.)


Please refer to the appropriate technical data sheet for the self-heating data, from the sine wave ripple current, as reference data. Please also utilize the software tool (Murata Chip Capacitor Characteristics Data Library) to obtain reference values for circuit design simulation.

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