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Old 06-20-2018, 08:20 AM   #1
John843883
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Default Choosing a Ceramic Multilayer Capacitor

Hi, I need to replace a Ceramic Multilayer Capacitor out of a car battery charger and was wondering which one to select? I've been reading up on those types of capacitors and have found out that they can change depending on applied voltage.

Here's the deal, I can't find anything related to this in the datasheets for the shortlist I have compiled. Its almost like the manufacturers would rather you didn't know this information.

The capacitor on the board had failed semi-short (150 ohm) so I can only guess the specs, but it looks to be about 1uF and is on the input of an op-amp. No idea what kind of voltage it see's but the op-amp does run off a 15v rail, its in series with a 4.7r resistor so probably does some RC stuff. The charger enclosure gets quite hot although it is fan cooled.

I know X7R is the best dielectric I can get in this size, but with manufacturers not publishing the voltage dependent capacitance and me not knowing what the charger subjects this capacitor to I'm having trouble deciding.

Anyone recognize some of the capacitor series in my shortlist care to point me in the right direction? This list was compiled based on availability in small quantities and current stock, there was a lot more currently out of stock or with massive minimum order quantities.

tl;dr Which of these capacitors are less likely to deviate in capacitance with applied voltage? The datasheets don't mention it.

Thanks.
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Old 06-20-2018, 11:46 AM   #2
PeteS in CA
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Default Re: Choosing a Ceramic Multilayer Capacitor

Here's something on X7R temperature coefficient from TDK.

And here's something on X7R voltage coefficient from Vishay.
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