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# Resonant capacitor for LLC converter

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#### cupoftea

Hi,
We wish to use 5 ECWHA3C223 (22nF) film capacitors in parallel as a resonant capacitance in an LLC converter.
The total current is 6Arms (100kHz sine) and voltage is +/-110V again sine 100kHz.

ECWHA3C223 22nF capacitor

Do you think it'll be ok?...i dont see an actual ripple current rating in the datasheet.

Why you are not using MLCC NP0?

keep reading the data sheet - it has all the information required to determine sensible current ratings, voltage ratings etc ...

For starters, 5 x 22nF = 110nF, @ 100kHz = 14.5 ohm, x 6A total = 87 Vrms = 123Vp.
--- Updated ---

D.F. = dissipation factor, Vrms * Irms * DF = watts ...

for a small cap, say 1-2cm^3, 300mW is about tops - unless you are direct force cooling ...

For starters, 5 x 22nF = 110nF, @ 100kHz = 14.5 ohm, x 6A total = 87 Vrms = 123Vp.
--- Updated Today at 10:34 AM ---

D.F. = dissipation factor, Vrms * Irms * DF = watts ...

for a small cap, say 1-2cm^3, 300mW is about tops - unless you are direct force cooling ...
Thanks, from datasheet kindly supplied by FvM, i see DF = 0.1% at 100kHz for the 22nF.
So from your kindly given equation i am getting 87 * 1.2 * 0.001 = 100mW per cap.
This seems to be OK.

The DF was in the data sheet posted in the 1st instance too - just needed a close look - be careful that caps are suitably de-rated for voltage - if you want them to last...
--- Updated ---

Which - at 1600V part - you appear to have done ...

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