[time-nuts] Low noise power supplies - dont' use Electrolytics

SAIDJACK at aol.com SAIDJACK at aol.com
Sat Nov 26 01:06:21 EST 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  
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. 
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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