ESD Capacitor Voltage Rating Selection

I want to know about the ESD capacitor with the “Part No: C0603C472K2RECAUTO” from the “ESD Protected X7R” series from the manufacturer “KEMET”. How shall we decide the suitable voltage rating for a ESD capacitor for a given ESD level? We have different voltage ratings (Vdc) for the same ESD level, so which one to choose? Please respond as soon as possible so that we can proceed with the purchase of this component.

The voltage rating of the cap should be chosen based on the voltage requirements of your circuit / application.

The ESD portion is a protection for the cap during assembly and operation and is not the cap’s rated voltage. If you need to pick a cap based on ESD voltage rating those specifications are on table 1A of the datasheet.

I have gone through the datasheet. I need a capacitor specifically for ESD protection only. It should withstand the required ESD levels during operation of the circuit & assembly as well. But I could see the same ESD levels for different rated voltages as well. So my doubt is which one should be chosen when both the value & ESD rating of the capacitors are same but only the voltage rating differs?

Another Question: It’s mentioned in datasheet that 250% of the rated voltage is the Dielectric Withstanding Voltage (DWV). Is DWV nothing but the “breakdown voltage” of the capacitor? What’s the difference between rated & breakdown voltage?

Looking at the data sheet you will see the rated voltage of the capacitor is the voltage rating for the circuit. What is the voltage of the circuit that needs this capacitor? If you have a 12V circuit you would likely need to pick a 16V or higher capacitor. This rating would be based solely on the needs of the circuit and not the ESD.

If you are looking at the ESD ratings you will see that those ratings vary based on the rated voltage, and capacity of the cap you are looking at.

So if you know you wanted 12kV of ESD protection on your circuit you can see that depending on the capacitance requirements you could have this level of protection in anything from a 16v to a 200V cap.
Here is a copy of the ESD table.


Rated voltage is what the capacitor is specified as being able to tolerate during normal operation, i.e. a 16V capacitor is (theoretically) able to tolerate being installed in a 16V circuit without undue deterioration. In practice you want to include a chunk of overhead and specify caps above your circuit voltage, but that’s what the spec means.

Dielectric withstand voltage is the amount of voltage the part can tolerate before the dielectric begins to break down, yes. Above that and you’re dealing immediate, permanent damage to the part.

Incidentally, rated voltage is important even if you’re using the capacitor strictly for ESD protection, as a capacitor installed in a circuit over its rated voltage will exhibit drastically reduced lifetime and poor operation, if it doesn’t malfunction altogether.