Siemens "Capacitor" Datasheet

Cound be 22 uF 16 volts tantalum.

Does it look like a tantalum?

Is it exploded like a tantalum?

John

That means nothing unless you have the schematic or BOM!

How about you post a photo so people don't have to randomly imagine what it is you are looking at?

Dave.

My wild guess is 22uF at 16V; wilder more crazy: tantalum SMT.

Siemens spun that biz off to Epcos. AFAIK they then sold the tantalum line to Kemet.

The op should take calipers, measure it and then use Digikey to locate the matching Kemet part if it is a tantalum. There's usually pics on the site, else click on the datasheet.

ROFL! That was a good one.

"Regards, Joerg (who avoids tantalum wherever possible)"

You'd rather use Al electrolytic?

George H.

Everyone always says avoid putting any voltage the least bit unusual on them, and never apply large peak currents. So, ironically, that rules them out for power supply bypass -- heavy bypass, like let's say a buck converter. Around digital logic, I bet it's not a big deal -- even a big stinking bus driver chip switching all outputs will draw well-defined peak currents. And anywhere the voltage can be weird, like oh let's say a poorly protected automotive supply rail.

Other than that, they're fairly ideal capacitors, good for bypass, low current / long duration timing, etc. Although I don't suppose anyone's recommended using a biased antiseries pair in filters.

What I find weird is, there's a teeny green blob style tantalum in my Heathkit oscilloscope. I didn't know they had caps like that back in the 70s. Maybe it isn't actually tantalum. What's strangest about it though, it's bypassing the vertical position control -- low current, just bulk capacitance, but gee, the voltage goes up and down by several volts, and it's returned to ground, not -V.

Tim

One excellent big-C, low-Z cap type is polymer aluminums. They seem to be reliable with large surge currents, at rated voltage, and don't have the failure and detonation mechanisms of MnO2 tantalums or the dryout/esr issues of wet aluminums. ESR is so low that some regulators may not like them.

I haven't tried the polymer tantalums or the niobium things.

Regular tantalums are fine if you can guarantee limited dV/dT, or if you can afford to derate them at least 3:1 on voltage. If not, they are time bombs, probably the least reliable thing you'll put on a board. We did one analysis that showed that tantalum caps accounted for half our field failures, of very complex boards with lots of other stuff going on. So we changed things.

John

Yes. Plus ceramics.

Thou shalt not use LDOs :-)

Sanyo OSCON are pretty good and it looks like Vishay has OSCON caps as well now. The downside is that they are very pricey. Epcos offers some really good large thru-hole electrolytics with ESR in the low tens of milliohms range. As with many European parts, availability in the US seems to be more challenging.

I've hung up on them right at the beginning of my industrial career back in the 80's, after a production tech's shirt was peppered with holes as a result of tantalums going phsooosh. Never looked back. They obviously did become better but IMHO not good enough. For coupling and timing purposes the may be ok though.

The UNITED CHEMICON polymers, from Digikey, are cheaper than tantalums for a given CV. We're buying 180 uF, 6.3 volts surfmount for around 80 cents. That's a lot more than a regular aluminum, but ESR is way, way lower.

They are fine as long as you don't force too much current into them. If you do, they tend to ignite: MnO2 is the oxidizer, tantalum is the fuel, the current is the detonator.

John

Looks like you are using these:

For some reason many younger engineers dismiss that, they say that's being paranoid. Until one fine day ... *KABLAM*