Capacitor Dissipation with Current Source

datasheet

Well, the best thing to do is to be able to measure it at the frequency of interest, and that's what I do all the time. However, having made many measurements and looked at lots of datasheets, I can tell you the DF probably doesn't decline too much at say 100kHz, where the esr for a 68nF film cap may well be under 0.1 ohm. At 1MHz, it's probably lower, but perhaps not by much, say about 0.05 ohm. So if you have 2A rms current (2.5V rms across the cap) at 1MHz, that would correspond to 0.2 watts, which is probably excessive for such a small part.

I'd say if you have in mind that much current at 1MHz with such a low value cap, then you'd better have very good specs for that part, or make some actual vector loss measurements for your cap. 0.02 ohms or less would be nice.

Use caps that specify the permissible AC voltage and current needed for your requirement. Here is one canidate: If the just give DF do not use!

datasheet

Ahh.. Do testing or seek better specs. Got it :)

I'm inclined to seek better specs. (Sorry Panasonic..but not enough specs..) I think it'll take me longer to set up my (crappy) test equipment to measure capacitor esr than to find a 'bigger' datasheet.

Thanks...

D from BC British Columbia Canada.

Cool.. Permissible Vrms graphs! Z graphs! That's better... Yup, I can use data like this. :)

Even though Vcap is triangular, it's nearly sine. Close enough for my app.

Thanks..

D from BC British Columbia Canada.