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

[SAIDJACK]

Were getting of off the original thread about Electrolytics versus other  
caps a bit..
 
>A switcher at 2.2MHz does not have single frequency spikes in its  power
>spectrum, but a rather wideband distribution.
 
Yes, that's Fourier 101 basics.
 
But what matters to Time nuts is if the switcher is running close to 1.0MHz 
 or 2.0MHz, as the 10th or 5th harmonics of these would fall right into the 
phase  noise spectrum of the 10.0MHz output and may show up on the usual 
phase noise  plots.
 
It is also easier to filter out a ~2MHz carrier than a ~1MHz carrier from  
AM-modulating our 10MHz oscillator through the power supply lines. Most of 
the  noise will likely be on the input of the buck switcher, not the output.
 
With a 1MHz switcher, you could have a nasty spur at 10.01MHz right in the  
spectrum of interest. Running at 2.2MHz moves that spur 1MHz away from the 
10MHz  carrier, and the possibility of the switcher "injection locking" with 
 the 10MHz oscillator is reduced. This is easier to accomplish with a 
2.2MHz  switcher than a 1MHz switcher.
 
>but a load-dependent feedback loop that will
>change duty cycle  or frequency (depending on device) to maintain a target
>output. Check for yourself.
 
The part I listed as an example is a fixed frequency device. Stay away  
from variable frequency devices for anything Time Nuts related - that is my  
opinion.
 
>Try to get >90% efficiency for instance, from 24V down to 3.5V 5A.  
Unlikely you can work at 2MHz.

A) why would you need 3.5V at 5A for anything time-nuts related?
 
B) you could parallel two or three 2MHz devices to get 5A output power, and 
 synchronize them to each other
 
C) If you are consuming 17.5 Watts at 3.5V in the first place, then  why 
would you care about 90% efficiency versus 85% efficiency in time-nuts  
related projects? The difference is less than one Watt, and getting 85% from 
24V  
should be possible with the switchers that are out there.
 
We now have commercial Cesium Vapor atomic clocks running at 0.12W and  
less, so it should be possible to get power consumption down way below  17.5W 
for most time nuts related equipment I would think...
 
bye,
Said
 
 
In a message dated 11/28/2011 16:43:03 Pacific Standard Time,  
camar...@quantacorp.com writes:

A  switcher at 2.2MHz does not have single frequency spikes in its  power
spectrum, but a rather wideband distribution. It is not a fixed  frequency,
fixed duty cycle oscillator, but a load-dependent feedback loop  that will
change duty cycle or frequency (depending on device) to maintain  a target
output. Check for yourself.

Try to get >90% efficiency  for instance, from 24V down to 3.5V 5A. Unlikely
you can work at  2MHz.


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

[Jose Camara]

A switcher at 2.2MHz does not have single frequency spikes in its power
spectrum, but a rather wideband distribution. It is not a fixed frequency,
fixed duty cycle oscillator, but a load-dependent feedback loop that will
change duty cycle or frequency (depending on device) to maintain a target
output. Check for yourself.

Try to get >90% efficiency for instance, from 24V down to 3.5V 5A. Unlikely
you can work at 2MHz.




-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of saidj...@aol.com
Sent: Monday, November 28, 2011 3:06 PM
To: time-nuts@febo.com
Subject: Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

Hi Attila,
 
I like >2MHz switchers because they use small components (inductors  and 
capacitors) and are easier to filter out at our usual frequencies of
interest.
 
The LT3502A for example works at 2.2MHz, which gives harmonics at 8.8MHz  
and 11MHz, far enough away from 10.0MHz to avoid beating and causing a spur

issue. The 1.1MHz part uses a 15uH inductor, the 2.2MHz part only a 4.7uH  
inductor for the same 1.8V, 500mA application example, a huge difference in 
size  and cost. The capacitor is also 22uF vs. 47uF, again a large size and 
cost  savings for the 2.2MHz part.
 
Not much of an efficiency difference between the 1MHz and 2MHz parts  
anymore, they are usually around 80% to 85% at 2.2MHz and one or two percent

better at 1.1MHz. With proper layout these parts are extremely well behaved
and 
 don't have any noticeable ringing etc on the switch as older units did, 
and they  don't create a lot of noise when using shielded inductors.
 
bye,
Said
 
 
In a message dated 11/28/2011 14:22:58 Pacific Standard Time,  
att...@kinali.ch writes:

> Use  ceramic caps where vibration is not an issue. Use high frequency   
> (>2MHz) switchers wherever efficiency is required, otherwise use  linear  
> regulators.

Not really. If you want to have good  efficiency, then you want to stay
below 1MHz, otherwise switching loses get  too high. But the disadvantage
is that you have big and bulky capacitors  and inductors. 

Staying somewhere between 1MHz and 1.5 is usually a  good compromise if
you can tolerate PFM (aka pulse skip) for low load  conditions. Going up
to 2MHz (and beyond) is only recomended if you are  severly space limited.


Attila Kinali


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

[SAIDJACK]

Hi Attila,
 
I like >2MHz switchers because they use small components (inductors  and 
capacitors) and are easier to filter out at our usual frequencies of  interest.
 
The LT3502A for example works at 2.2MHz, which gives harmonics at 8.8MHz  
and 11MHz, far enough away from 10.0MHz to avoid beating and causing a spur  
issue. The 1.1MHz part uses a 15uH inductor, the 2.2MHz part only a 4.7uH  
inductor for the same 1.8V, 500mA application example, a huge difference in 
size  and cost. The capacitor is also 22uF vs. 47uF, again a large size and 
cost  savings for the 2.2MHz part.
 
Not much of an efficiency difference between the 1MHz and 2MHz parts  
anymore, they are usually around 80% to 85% at 2.2MHz and one or two percent  
better at 1.1MHz. With proper layout these parts are extremely well behaved and 
 don't have any noticeable ringing etc on the switch as older units did, 
and they  don't create a lot of noise when using shielded inductors.
 
bye,
Said
 
 
In a message dated 11/28/2011 14:22:58 Pacific Standard Time,  
att...@kinali.ch writes:

> Use  ceramic caps where vibration is not an issue. Use high frequency   
> (>2MHz) switchers wherever efficiency is required, otherwise use  linear  
> regulators.

Not really. If you want to have good  efficiency, then you want to stay
below 1MHz, otherwise switching loses get  too high. But the disadvantage
is that you have big and bulky capacitors  and inductors. 

Staying somewhere between 1MHz and 1.5 is usually a  good compromise if
you can tolerate PFM (aka pulse skip) for low load  conditions. Going up
to 2MHz (and beyond) is only recomended if you are  severly space limited.


Attila Kinali


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

[Attila Kinali]

On Mon, 28 Nov 2011 16:16:58 -0500 (EST)
saidj...@aol.com wrote:

> Use foil caps to avoid vibration-microphonics. Very expensive, but hey you  
> get what you pay for. Use Tantalum caps if bulk bypassing is needed, using  
> multiple 100uF units if necessary. The design is not right if you need more 
> than  say 470uF anyways unless you are switching tens of amps as in an 
> Audio power  amp..

I can agree on that, though i also had a design where i used 5*100uF
and it was barely enough (a system that usually used just a couple of
mA, but occasionaly could draw up to 2A for half a second. Of course,
the power supply could only deliver about 500mA)
  
> Use ceramic caps where vibration is not an issue. Use high frequency  
> (>2MHz) switchers wherever efficiency is required, otherwise use linear  
> regulators.

Not really. If you want to have good efficiency, then you want to stay
below 1MHz, otherwise switching loses get too high. But the disadvantage
is that you have big and bulky capacitors and inductors. 

Staying somewhere between 1MHz and 1.5 is usually a good compromise if
you can tolerate PFM (aka pulse skip) for low load conditions. Going up
to 2MHz (and beyond) is only recomended if you are severly space limited.


Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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

[SAIDJACK]

Hi guys,
 
yes, Electrolytics, the OS-CON are specified at an internal +20C  
temperature rise when running at rated AC current, and that's probably when 
they  are 
brand-new and have all of their initial capacitance. Temperature rise in  
high current apps will probably increase as the part ages and looses  
capacitance.
 
Electronics in an enclosure can easily run at +30C above ambient due  to 
self heating, so +50C to ambient on the capacitor can easily happen. With a  
30C ambient, we are looking at 80C on the cap, and are down to a year 
lifetime  again on the standard OS-con caps (they seem to have long-lifetime 
special  models available too which are probably much more expensive). Let's 
keep 
in mind  that the OS-Con caps standard lifetime versions are already very 
expensive in my  opinion.

Also, Sanyo specifies "lifetime" not MTBF! Assuming this means useful  
lifetime with less than 50% decrease in capacity, this may mean that the MTBF 
is 
 actually much lower than that, since many designs may not work properly 
with  -50% capacitance, or have more than +20C self heating on the cap.
 
We have to remember that it may work on a particular installation for years 
 on end especially if it used as a DC bypass cap without any AC current on 
it,  but when designing products we cannot rely on anecdotal information, 
but rather  have to do the math based on the parts' specsheet and the products 
expected  worst-case ambient environment.
 
In my opinion:
 
Use foil caps to avoid vibration-microphonics. Very expensive, but hey you  
get what you pay for. Use Tantalum caps if bulk bypassing is needed, using  
multiple 100uF units if necessary. The design is not right if you need more 
than  say 470uF anyways unless you are switching tens of amps as in an 
Audio power  amp..
 
Use ceramic caps where vibration is not an issue. Use high frequency  
(>2MHz) switchers wherever efficiency is required, otherwise use linear  
regulators.
 
Use electrolytics ONLY in external disposable low-cost power supplies, such 
 as the $15, 12V 1A Wall Wart supplies available at Mouser etc.
 
Just my own opinions..
 
bye,
Said
 
 
In a message dated 11/27/2011 23:22:08 Pacific Standard Time,  
att...@kinali.ch writes:

On Fri,  25 Nov 2011 22:25:37 -0800
Chris Albertson   wrote:

> One question:  How  does one avoid using electrolytic caps if you need
> (say) 1,000uF or  even 100uF.   Those would be some mighty big film
>  caps.

I think, aluminium electrolytics are meant, as these have a lot  of
"wear" and can die. 

Hence, you can use tantal or niob  electrolytics, which have a dry
eletrolyt.

Or you can use ceramics  which are already available at 100uF.

Attila Kinali

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

[Attila Kinali]

On Mon, 28 Nov 2011 01:05:22 -0800
gary  wrote:

> Ceramic caps can be microphonic. Just something to be on the look out. 
> Not so much with leaded ceramics, but more of a problem with surface mounts.

Ceramic caps have a lot of other problems too, like capacitance
derating on increasing voltage. Some types go down to 80% of rated
capacity when driven to the max rated voltage.
 
> Tantalums are prone to overvoltage failure. Best to really overspec them 
> regarding voltage.

Uhmm.. overspec? The rated voltage is the maximum allowed voltage.
Like something you should never cross. That's why we have these
odd numbers like 16V. They are not intended to be used at 16V but
rather at standard voltages like 12V.


> Note that some LDOs are not stable with really low ESR bypass. There are 
> app notes on this. 

Actually, the datasheet of any LDO (or power regulator) should define
the stable operation output capacitance and ESR. If you work outside
the speced range.. well.. your own fault if you get oscillation ;-)



Attila Kinali

-- 
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin

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

[gary]

Ceramic caps can be microphonic. Just something to be on the look out. 
Not so much with leaded ceramics, but more of a problem with surface mounts.


Tantalums are prone to overvoltage failure. Best to really overspec them 
regarding voltage.


Note that some LDOs are not stable with really low ESR bypass. There are 
app notes on this. I've stated my preference for p-fet pass devices, or 
better yet, shunt regulators. The PNP pass devices will need feedforward 
compensation if the ESR is too low.



On 11/27/2011 11:21 PM, Attila Kinali wrote:

On Fri, 25 Nov 2011 22:25:37 -0800
Chris Albertson  wrote:


One question:  How does one avoid using electrolytic caps if you need
(say) 1,000uF or even 100uF.   Those would be some mighty big film
caps.


I think, aluminium electrolytics are meant, as these have a lot of
"wear" and can die.

Hence, you can use tantal or niob electrolytics, which have a dry
eletrolyt.

Or you can use ceramics which are already available at 100uF.

Attila Kinali



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

[Attila Kinali]

On Fri, 25 Nov 2011 22:25:37 -0800
Chris Albertson  wrote:

> One question:  How does one avoid using electrolytic caps if you need
> (say) 1,000uF or even 100uF.   Those would be some mighty big film
> caps.

I think, aluminium electrolytics are meant, as these have a lot of
"wear" and can die. 

Hence, you can use tantal or niob electrolytics, which have a dry
eletrolyt.

Or you can use ceramics which are already available at 100uF.

Attila Kinali

-- 
Why does it take years to find the answers to
the questions one should have asked long ago?

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

[ehydra]

I molt them in a high-power charge-pump. The same with WIMA MKS.

At normal usage they will last forever and work even at low temperature 
whereas normal Al caps won't.


- Henry


gary schrieb:
At sane temperatures, OSCONs are very good. Who runs their gear hot 
enough to boil water?

http://edc.sanyo.com/pdf/e_oscon.pdf


--
ehydra.dyndns.info

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

[Jim Lux]

On 11/26/11 11:13 AM, Chris Albertson wrote:

On Fri, Nov 25, 2011 at 10:36 PM, Raj  wrote:

How about this way: Amplifying capacitance.. (Base/Ground cap * Beta)

http://sound.westhost.com/project15.htm



The above actually uses several quite large electrolytic.   It is a
good example of why you NEED to use them.

Maybe someone can post a schematic of a simple  5V 5A power supply
that does NOT use any electro caps.




WHat ripple/regulation?

3 phase power and no filter gives you 8% ripple.




Chris Albertson
Redondo Beach, California

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

[Chris Albertson]

On Fri, Nov 25, 2011 at 10:36 PM, Raj  wrote:
> How about this way: Amplifying capacitance.. (Base/Ground cap * Beta)
>
> http://sound.westhost.com/project15.htm
>

The above actually uses several quite large electrolytic.   It is a
good example of why you NEED to use them.

Maybe someone can post a schematic of a simple  5V 5A power supply
that does NOT use any electro caps.


Chris Albertson
Redondo Beach, California

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

[ed breya]

Off topic: Actually, you can make almost anything withstand almost 
any conditions TEMPORARILY - it depends on the packaging too. If you 
wrap a circuit that can work at 100 deg C in a water jacket wrapped 
in high temperature insulation, you can keep it going until most of 
the water has boiled away. That's how those so-called fire safes can 
protect papers against fire for a certain amount of time - the 
insulation is hydrated gypsum, which insulates and provides cooling water.


On topic: You can use whatever capacitors make sense for the 
application, but you know that the hotter they need to run, the less 
life is to be expected.


Ed

On Sat, Nov 26, 2011 at 2:13 AM, gary 
<lists at 
lazygranch.com> wrote:

> At sane temperatures, OSCONs are very good. Who runs their gear hot enough
> to boil water?

Sat Nov 26 12:53:13 UTC 2011  Bob Paddock bob.paddock at gmail.com  wrote:

National Fire Protection Agency (NFPA) 2007 edition of their design
regulations state the electronics worn by Fire Fighters must work at
500'F for five minutes.
In the Paper Pusher's mind the Kevlar clothing can withstand those
temperatures, therefor anything else in the Universe can too.
Never under estimate the bureaucratic mind...




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

[Bob Paddock]

On Sat, Nov 26, 2011 at 2:13 AM, gary  wrote:
> At sane temperatures, OSCONs are very good. Who runs their gear hot enough
> to boil water?

National Fire Protection Agency (NFPA) 2007 edition of their design
regulations state the electronics worn by Fire Fighters must work at
500'F for five minutes.
In the Paper Pusher's mind the Kevlar clothing can withstand those
temperatures, therefor anything else in the Universe can too.
Never under estimate the bureaucratic mind...

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

[Poul-Henning Kamp]

In message 
, Chris Albertson writes:

>One question:  How does one avoid using electrolytic caps if you need
>(say) 1,000uF or even 100uF.   Those would be some mighty big film caps.

One detail, often overlooked, is that electrolytics seldom are
dimensioned very precisely, mostly because they do come with such
big capacity but also because them have very big tolerances, +/-
50% is not uncommon.

Another effect that causes overdimensioning is that they are not very
good capacitors, in particular at higher frequency.

I have in a couple of instances replaced electrolytics with film-caps
and gotten away with less than 1% of the original capacitance by doing
a bit of calculations and measurements on the actual circuit.

In one case, an audio circuit had 1000uF for a handful of opamps,
using 4.7uF of good film capacitors instead reduced THD by 80%.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

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

[gary]

At sane temperatures, OSCONs are very good. Who runs their gear hot 
enough to boil water?

http://edc.sanyo.com/pdf/e_oscon.pdf




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

[Steve .]

To second the older electronics:

I maintain nearly 100 analytical instruments. The old designs(1970-late
80's) are almost all electrolytic caps and none of the caps have ever
failed. When I do find a bad cap it's always in a modern design. A high
frequency switcher with under rated caps. When i say under rated i mean
take the peak figure and multiple it by two, that's the real part value.

My opinion, bad designs.

Steve

On Sat, Nov 26, 2011 at 1:25 AM, Chris Albertson
wrote:

> Many of us have seen electronic equipment last longer then one year.
> Some of use even have still working antiques with old eletro caps.
> Those short lifetimes assume a worse case, usually with a very high
> ripple current.   IOf you can reduce the ripple the MTBF goes up.
>
> One question:  How does one avoid using electrolytic caps if you need
> (say) 1,000uF or even 100uF.   Those would be some mighty big film
> caps.
>
>
>
>
> On Fri, Nov 25, 2011 at 10:06 PM,   wrote:
> > 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,
> > li...@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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> >
>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
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Re: [time-nuts] Low noise power supplies - dont' use Electrolytics

[Raj]

How about this way: Amplifying capacitance.. (Base/Ground cap * Beta)

http://sound.westhost.com/project15.htm


>One question:  How does one avoid using electrolytic caps if you need
>(say) 1,000uF or even 100uF.   Those would be some mighty big film
>caps.


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

[Chris Albertson]

Many of us have seen electronic equipment last longer then one year.
Some of use even have still working antiques with old eletro caps.
Those short lifetimes assume a worse case, usually with a very high
ripple current.   IOf you can reduce the ripple the MTBF goes up.

One question:  How does one avoid using electrolytic caps if you need
(say) 1,000uF or even 100uF.   Those would be some mighty big film
caps.




On Fri, Nov 25, 2011 at 10:06 PM,   wrote:
> 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,
> li...@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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>



-- 

Chris Albertson
Redondo Beach, California

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

[SAIDJACK]

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,  
li...@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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