C0G AC derating

Hi,

Polypropylene capacitors are no longer the only choice in the ~20nF/1kV+ range. Now there are C0G MLCCs as well. It makes me think whether they would work reliably as the LLC resonant capcitors, in split capacitor resonant half-bridge topology preferably. The polypropylene high frequency derating curves are available, but I see no similar specification for the ceramics. So is there any derating needed, besides the obvious dissipation factor/ESR limited heating?

Best regards, Piotr

Reply to
Piotr Wyderski
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We used 2 630V caps in a split arrangement, single half bridge driver LLC 230V converter - and had good margin

AFAIR it was a TDK C0G

I can look specific part number up tomorrow

Cheers

Klaus

Reply to
Klaus Kragelund

Only current AFAIK.

You sometimes see current ratings in the datasheet, but if not, a good guess would be to limit power dissipation to half that of a resistor in the same package. So, 1206, 62mW, etc. Then use ESR from the Z(F) curve to get current.

Even with induction heating experiments, I can't recall actually making them heat up. They handle a lot of VAs.

I put a 47nF C0G in a recent LLC resonant project (mind, only 10W), doesn't get perceptibly warm by itself (it's all the other stuff around it that's getting hot).

Tim

-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:

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Reply to
Tim Williams

We used this one:

CGA5C4C0G2J151J060AA

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Reply to
Klaus Kragelund

Rats, no current rating:

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(it should be in the char/data-sheet PDF if present; it's more obvious in this view, I guess)

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Design 
Website: https://www.seventransistorlabs.com/
Reply to
Tim Williams

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