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It absolutely depends on the application. We use bucketloads of low ESR tantalum capacitors from AVX. They test them at the factory and sell them in different ESR grades. The ESR grade is actually printed on them.
We also use Sanyo OS-Cons in SMD packages, a little aluminium can on a plastic carrier. The ESR is in the tens of milliohms and they'll stand several amps of ripple all day. Remarkable for such a tiny part, but they do cost several bucks each!
We also use a lot of "standard" electrolytic capacitors which I expect to have an ESR of a few ohms. This actually helps to damp resonances in power rail bypassing applications. For example, 3 terminal regulators will sometimes oscillate if the bypass capacitor doesn't have enough ESR. This is why the datasheet says to use electrolytic bypass caps, not plastic film.
We call out the low ESR capacitors on the schematics we publish, so service guys will know to replace them with equivalent parts.
We also use Sanyo OS-Cons in SMD packages, a little aluminium can on a plastic carrier. The ESR is in the tens of milliohms and they'll stand several amps of ripple all day. Remarkable for such a tiny part, but they do cost several bucks each!
We also use a lot of "standard" electrolytic capacitors which I expect to have an ESR of a few ohms. This actually helps to damp resonances in power rail bypassing applications. For example, 3 terminal regulators will sometimes oscillate if the bypass capacitor doesn't have enough ESR. This is why the datasheet says to use electrolytic bypass caps, not plastic film.
We call out the low ESR capacitors on the schematics we publish, so service guys will know to replace them with equivalent parts.
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