Capacitor Selection

[JohnsonMiller]

Hi Guys,

I am dealing with capacitor selection, but caps need to be low-leakage.
I got one recommendation that at same capacitance value, bigger packages are usually low ESR, which make sense.
Do you think we can choose a big package for low leakage as well? What about voltage rating and leakage, can we say at the same value and same package, higher voltage rating will have lower leakage?

[robertferanec]

I am not any super expert for capacitors, however I am not sure if low ESR influences low-leakage. I would say that may be a different parameter. When you say low-leakage I imagine a capacitor which will be discharging itself very slowly: https://www.digikey.com/eewiki/displ...+of+Capacitors

[WhoKnewKnows]

From a few designs where capacitor leakage was a concern, I know that leakage current increases as the capacitor's voltage approaches the capacitor's rated voltage. I'm not certain that translates to all capacitor constructions. If so, it would seem that a strategy for minimizing leakage would be to spec capacitors with much higher voltage rating than otherwise needed. Also, keep in mind, some capacitor types, electrolytics, perhaps others, become more leaky from disuse. To test and compare, you may have to reform them first.

[qdrives]

https://www.murata.com/en-eu/support/faqs/products/capacitor/mlcc/char/0039

Difference can also be the dielectric (NP0 vs X7R)