[time-nuts] Low noise power supplies - dont' use Electrolytics
SAIDJACK at aol.com
SAIDJACK at aol.com
Sat Nov 26 06:06:21 UTC 2011
Electrolytic caps have an extremely poor lifetime (MTBF). Sanyo on their
website state "50K Hrs at 50C".
This means only 6250 MTBF hours at 80C for one single cap. MTBF gets worse
the more caps are being used of course. I have seen some Panasonic
electrolytics state only 2000 hours MTBF at temperature in their datasheets.
That's not even one year before a mean failure occurs making these useless
in high-reliability applications.
Note also that caps in high AC current situations (Buck DC-DC switcher
input cap for example) will self heat due to internal resistance, making things
even worse. This is probably one of the main failure reasons for PC
motherboards.
And that's with name brand parts, it's even worse if one ends up buying
counter-fit or non-name-brand Electrolytics.
Some of our competitors use Electrolytics all over the place (we don't use
any electrolytics) - that's been good for our business.
bye,
Said
In a message dated 11/24/2011 17:08:42 Pacific Standard Time,
lists at lazygranch.com writes:
I'm not familiar with rubycon caps. The low ESR large value caps are
"organic semiconductor." OSCON is a common brand from Sanyo. Finding the
ultimate cap is nearly as much fun as finding the ultimate LDO. Check
out Nichicon. Or you can stick with the Rubycon. Glancing at their
website, they seem to copy the Nichicon product line.
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