Just eyeballing it, it seems you might put two caps in series and have greater total capacitance than with a single cap at 55V.
A better approach would be to use a curve fitting routine to get a least squares curve fit, then calculate the capacitance vs voltage.
Or just put two caps in series and measure the capacitance.
Blimey! You are right! Two of those caps in series gets you more capacitance than those same two in parallel. That takes some getting used to. One gets the impression the manufacturers overdid something.
Jeroen Belleman
Blimey! Are you sure? Two caps in parallel would be
0.385 * 2 = 0.77 uFTwo caps in series would be 0.5325 uF
What really alarms me is the temperature coefficient:
The above is from
If you use these as bypass caps, they can resonate with supply inductances and generate large voltages on the supply. But if the temperature changes, say during warmup, the problem could come and go. This makes troubleshooting difficult.
I wonder if these caps are that much cheaper than C0G or NP0 to make it worth while stocking them. Simply placing the part on the pcb can cost more then the part, so I wonder if there is any cost savings to go with cheap caps.
Ah, I got carried away and posted too quickly, is true. It's not *that* bad. It's probably impossible by reason of conservation of energy, or something. I have to think this over a bit more.
Very non-linear capacitance is interesting in its own right, for parametric circuits, mixers, amplifiers and such.
Jeroen Belleman
It looks like C*V may be declining a bit above 25 volts maybe, so series caps may have a bit more C than parallel. But ESR and ESL will increase if they are in series. My application is pulsed power, so I want low impedance.
I'm currently using two 1206 ceramics in parallel with a 10uF aluminum per HV output channel.
Nichicon has a 10uF 63V polymer cap, which would be great for this application. Maybe I should add that to stock.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I guess any cap will explode if you stuff too much energy into it. A film cap just gobbles energy by V-squared until it fails. At least a hi-K ceramic tries to protect itself by ratcheting down C.
The 50V cap that I tested to failure, at 480 volts, has a hole blown in the side.
A ceramic cap could be an interesting parametric amplifier. Somebody sells a varicap-like device that's actually ceramic based.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I was pretty sure you didn't mean it. Probably need more coffee in the morning.
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