[sdiy] Tantalums, ESR

[Jerry Gray-Eskue]

Here is some more info on the timeline of and various types of tantalum
caps, note that this may not be totally up to date on all variations.

The comments about "Low ripple current ratings" ( result of high ESR ) may
not be true of all current variations.

http://www.radio-electronics.com/info/data/capacitor/tantalum-capacitor.php

Part of what is said is:

[The tantalum foil capacitor was introduced around 1950. ... Initially plain
foil variants were introduced, but this was quickly followed by etched
variants.
...
Tantalum capacitors with porous anode and solid electrolyte:  ... it is the
variety that is most commonly used. ...
These capacitors are superior to electrolytic capacitors in many ways
exhibiting excellent temperature and frequency characteristics. They are
also smaller than their aluminum electrolytic counterparts. However they are
not able to handle high levels of current or voltage spikes. They are also
damaged almost instantaneously by reverse polarity - usually exploding quite
nicely.
...

Tantalum capacitors have a number of disadvantages, and these need to be
considered when using them in new designs.
...
Low ripple current ratings: It is hardly surprising in view of their size,
that tantalum capacitors do not have a high ripple current rating. They
should not normally be used in areas that require any levels of current to
be passed.]



-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Jerry
Gray-Eskue
Sent: Wednesday, June 10, 2009 9:34 PM
To: Synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] Tantalums, ESR



I believe Both are true, capacitor technology has made a lot of progress
since the 1970's. I think that the tantalum caps in the very old gear will
have the higher ESR. The low ESR tantalum I believe is a later development,
they were always low leakage.

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of Ingo Debus
Sent: Thursday, June 11, 2009 8:07 AM
To: synthdiy DIY
Subject: [sdiy] Tantalums, ESR



Am 11.06.2009 um 01:13 schrieb Jerry Gray-Eskue:

> The big difference is the
> tantalum has a significantly higher ESR



Am 11.06.2009 um 01:11 schrieb John Henson:

> back in the days tantalum capacitors had (still have} two redeeming
> features...
> Low leakage and very low ESR.

Now, which is true? ;-)

Browsing some random datasheets I find both high and low values for
both capacitor types...

Ingo
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