Capacitance versus voltage for X7S caps?

Do you really want to see the cap drop by 80%?

I want to know where it does. One reason for that is to be able to model overvoltage spikes somewhat properly.

A cap that's spec'd at 100V ought to have graphs that go to 100V. Why don't they do that? From experience I can tell you that this would raise the hackles at agency testing. And that's never a good thing to happen :-)

My latest tool for modeling such phenomenon, GetData Graph Digitizer:

It can "read" a data sheet graph and generate a PWL or table fit.

...Jim Thompson

Yes, you had mentioned it. However, there ain't no datasheet data provided for this here part. At least it's incomplete. I see that happen a lot lately :-(

Measure it yourself, then add that behavior to your simulation... if you use such modern tools :-) ...Jim Thompson

Well ... the design had to be done by evening to go into layout next day. Even Fedex doesn't yet provide supersonic jets plus the 4500ft runway here in town would be kinda scary to land one of those and there's a hill in the straight approach path. Two people have died on it already :-(

I do use a computation machine with a simulator on there. For the LC stuff I used a slide rule though :-)

electrical=20

that=20

graph=20

About 1/2 cubic inch any way you pack it. Alternatively i might try the aluminum polymer electrolytics.

"Electrolytic" makes an alarm bell go off in my head against expectation of capacitance refusing to vary with voltage.

Is there a reason for polymer to fix this for aluminum electrolytics?

- Don Klipstein ( snipped-for-privacy@misty.com)

Tantalums are quite excellent (typically 10%, stable enough e.g. for long period timing), but they have a tendancy to explode.

By removing the moist electrolyte from the capacitor, replacing it with a conductive organic polymer, the alpos get tantalum grade performance without the risk of incineration.

Tim

They aren't that big anymore. You can get X7R in 2220 but that size is already causing concern WRT stress fracture.

If I could get them in 2.5mm height or less. Plus there's the issue of freezing.

Do you know how they take hardcore freezes, like north of the Klondike in January?

I have used Oscons on another project. They are very expensive and in this case I need 100V and the height cannot be more than 2.5mm or around

Oscon aluminum organic polymer are characterized to -55degC., with less than 10% cap reduction. At 4.7uF, ESR is in the 80mR range.

Later developers tend to follow this.

RL

graph

Freezing? Are your catheters used on Demonicrats too? What ever would they be looking for?

that

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No, medical is not the only branch I am designing for. It's actually less and less medical which is sort of a good thing (can't get PL coverage because of that). Aerospace, industrial, harsh environment stuff, and so on.

that

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You had me wondering there. ;-)

that

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Can you get PL if it's only industrial?

I find, as soon as you say "computer", the insurance companies run for cover. I don't understand why. ...Jim Thompson

that

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AFAICT yes. But if the box "Do you design medical electronics?" is checked you are instantly a pariah.

They like to only insure underwater carpet fires. Heck, they even exclude recalls which makes the whole PL concept pointless for anyone who designs products. I mean, what are they thinking that engineers do? Research in some ivory tower all day long and write nice papers in LaTex?

A chat with an underwriter a few years ago: "So you design products, huh?" ... "Yeah." ... "So how long do they typically remain in production?" ... "Oh, 10, 15 years." ... *THUD*

I'm not sure if you've actually stated your requirement at some time or another. You seem to be merely floating generalized but limited questions regarding part characteristics.

What is the actual requirement?

RL