Capacitance versus voltage for X7S caps?

Started by Joerg March 24, 2010
Tried the major mfgs and the typical datasheet looks like this:

http://www.avx.com/docs/Catalogs/cx7s.pdf

Quote "Capacitance for X7S varies under the influence of electrical 
operating conditions such as voltage and frequency."

Then under diagrams ... nada, zip, zilch. Great.

One paper listed X7S with the same voltage coefficient as X7R but that 
doesn't sound right. Anyone have a link to some hard data, with a graph 
in there and preferably no marketing hype?

-- 
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Joerg wrote:
> Tried the major mfgs and the typical datasheet looks like this: > > http://www.avx.com/docs/Catalogs/cx7s.pdf > > Quote "Capacitance for X7S varies under the influence of electrical > operating conditions such as voltage and frequency." > > Then under diagrams ... nada, zip, zilch. Great. > > One paper listed X7S with the same voltage coefficient as X7R but that > doesn't sound right. Anyone have a link to some hard data, with a graph > in there and preferably no marketing hype?
Joerg, Not too long ago I was also looking for C(V) dependencies for different capacitor types; didn't find much useful information either. One of the reasons for that is C(V) behavior of particular cap is strongly affected by electrostatic mechanical (!) effects; thus, at low frequencies, it is too much of dependency from everything. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
Joerg a écrit :
> Tried the major mfgs and the typical datasheet looks like this: > > http://www.avx.com/docs/Catalogs/cx7s.pdf > > Quote "Capacitance for X7S varies under the influence of electrical > operating conditions such as voltage and frequency." > > Then under diagrams ... nada, zip, zilch. Great. > > One paper listed X7S with the same voltage coefficient as X7R but that > doesn't sound right. Anyone have a link to some hard data, with a graph > in there and preferably no marketing hype? >
I looked at that recently but for X7R/X5R. Data sheets often have nothing, but the good manufacturers offer some 'simulation' program with lots of curve fitting,... IIRC TDK has some web base one too. I think Kemet, AVX, Murata, Taiyo have what you're after. -- Thanks, Fred.
On Wed, 24 Mar 2010 16:22:59 -0700, Joerg
<invalid@invalid.invalid> wrote:

>Tried the major mfgs and the typical datasheet looks like this: > >http://www.avx.com/docs/Catalogs/cx7s.pdf > >Quote "Capacitance for X7S varies under the influence of electrical >operating conditions such as voltage and frequency." > >Then under diagrams ... nada, zip, zilch. Great. > >One paper listed X7S with the same voltage coefficient as X7R but that >doesn't sound right. Anyone have a link to some hard data, with a graph >in there and preferably no marketing hype?
I seem to recall reading that C0G and NP0 dielectrics have the lowest cap-vs-temp dependance and that pretty much everyone "understands" that X7R dielectrics have large coefficients and are pretty much unsuitable where it matters. They pack a lot of capacitance into a small space and that makes them great for decoupling jobs and not so much else. But I don't know remember reading anything about X7S, specifically. If they are the same as X7R, they are crap if what else I read was right. Jon
Fred Bartoli wrote:
> Joerg a écrit : >> Tried the major mfgs and the typical datasheet looks like this: >> >> http://www.avx.com/docs/Catalogs/cx7s.pdf >> >> Quote "Capacitance for X7S varies under the influence of electrical >> operating conditions such as voltage and frequency." >> >> Then under diagrams ... nada, zip, zilch. Great. >> >> One paper listed X7S with the same voltage coefficient as X7R but that >> doesn't sound right. Anyone have a link to some hard data, with a >> graph in there and preferably no marketing hype? >> > > I looked at that recently but for X7R/X5R. Data sheets often have > nothing, but the good manufacturers offer some 'simulation' program with > lots of curve fitting,... > > IIRC TDK has some web base one too. > I think Kemet, AVX, Murata, Taiyo have what you're after. >
I've been through those. My impression was that a lot of docs I used to see there have been "cleaned out". I need something in the form of a document, not a simulator. Also, other than SPICE and beam field simulators I don't trust them. For example, National has flagged all my first switchmode converter ideas as "can't be done". And all went into mass production without a hitch ... -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Jon Kirwan wrote:
> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg > <invalid@invalid.invalid> wrote: > >> Tried the major mfgs and the typical datasheet looks like this: >> >> http://www.avx.com/docs/Catalogs/cx7s.pdf >> >> Quote "Capacitance for X7S varies under the influence of electrical >> operating conditions such as voltage and frequency." >> >> Then under diagrams ... nada, zip, zilch. Great. >> >> One paper listed X7S with the same voltage coefficient as X7R but that >> doesn't sound right. Anyone have a link to some hard data, with a graph >> in there and preferably no marketing hype? > > I seem to recall reading that C0G and NP0 dielectrics have > the lowest cap-vs-temp dependance and that pretty much > everyone "understands" that X7R dielectrics have large > coefficients and are pretty much unsuitable where it matters. > They pack a lot of capacitance into a small space and that > makes them great for decoupling jobs and not so much else. > > But I don't know remember reading anything about X7S, > specifically. If they are the same as X7R, they are crap if > what else I read was right. >
The lousy ones are Y5V and Z5U. X7R is actually pretty good. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
On Wed, 24 Mar 2010 17:41:39 -0700, the renowned Joerg
<invalid@invalid.invalid> wrote:

>Jon Kirwan wrote: >> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >> <invalid@invalid.invalid> wrote: >> >>> Tried the major mfgs and the typical datasheet looks like this: >>> >>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>> >>> Quote "Capacitance for X7S varies under the influence of electrical >>> operating conditions such as voltage and frequency." >>> >>> Then under diagrams ... nada, zip, zilch. Great. >>> >>> One paper listed X7S with the same voltage coefficient as X7R but that >>> doesn't sound right. Anyone have a link to some hard data, with a graph >>> in there and preferably no marketing hype? >> >> I seem to recall reading that C0G and NP0 dielectrics have >> the lowest cap-vs-temp dependance and that pretty much >> everyone "understands" that X7R dielectrics have large >> coefficients and are pretty much unsuitable where it matters. >> They pack a lot of capacitance into a small space and that >> makes them great for decoupling jobs and not so much else. >> >> But I don't know remember reading anything about X7S, >> specifically. If they are the same as X7R, they are crap if >> what else I read was right. >> > >The lousy ones are Y5V and Z5U. X7R is actually pretty good.
For low values of "pretty good". I suppose losing 20% of capacitance due to voltage and/or 5% due to temperature and/or a few more percent due to aging is better than -80% or whatever.. NP0 are now available (though a bit pricey and bulky) even in fairly large values like 0.1uF 1206. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
On Wed, 24 Mar 2010 17:41:39 -0700, Joerg
<invalid@invalid.invalid> wrote:

>Jon Kirwan wrote: >> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >> <invalid@invalid.invalid> wrote: >> >>> Tried the major mfgs and the typical datasheet looks like this: >>> >>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>> >>> Quote "Capacitance for X7S varies under the influence of electrical >>> operating conditions such as voltage and frequency." >>> >>> Then under diagrams ... nada, zip, zilch. Great. >>> >>> One paper listed X7S with the same voltage coefficient as X7R but that >>> doesn't sound right. Anyone have a link to some hard data, with a graph >>> in there and preferably no marketing hype? >> >> I seem to recall reading that C0G and NP0 dielectrics have >> the lowest cap-vs-temp dependance and that pretty much >> everyone "understands" that X7R dielectrics have large >> coefficients and are pretty much unsuitable where it matters. >> They pack a lot of capacitance into a small space and that >> makes them great for decoupling jobs and not so much else. >> >> But I don't know remember reading anything about X7S, >> specifically. If they are the same as X7R, they are crap if >> what else I read was right. > >The lousy ones are Y5V and Z5U. X7R is actually pretty good.
X7R is bad enough that it distorts like hell in an audio amplifier (used as the Miller cap) and I know I certainly can't even come close to using them in integrators, from actual (hilarious, for a moment) experience. Decoupling is what they are good for. Jon
"Jon Kirwan" <jonk@infinitefactors.org> wrote in message 
news:9uklq5hjvgr6kjttlagugqd55hfod2gohv@4ax.com...
> X7R is bad enough that it distorts like hell in an audio > amplifier (used as the Miller cap) and I know I certainly > can't even come close to using them in integrators, from > actual (hilarious, for a moment) experience. Decoupling is > what they are good for.
Unsurprisingly, the integration curve (step input) looks just like a high permeability, ungapped ferrite inductor's. You're just tracing out the D-E curve instead of the B-H curve. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
On Wed, 24 Mar 2010 16:22:59 -0700, Joerg <invalid@invalid.invalid>
wrote:

> Tried the major mfgs and the typical datasheet looks like this: > > http://www.avx.com/docs/Catalogs/cx7s.pdf > > Quote "Capacitance for X7S varies under the influence of electrical > operating conditions such as voltage and frequency."
http://web.archive.org/web/20070206080241/http://members.aol.com/sbench102/cap.html http://web.archive.org/web/20070912104727/http://members.aol.com/sbench102/caps.html http://web.archive.org/web/20080203162906/http://members.aol.com/sbench102/caps1.html http://web.archive.org/web/20071107034022/http://members.aol.com/sbench102/caps2.html
JosephKK wrote:
> On Thu, 01 Apr 2010 10:07:24 -0700, Joerg <invalid@invalid.invalid> wrote: > >> JosephKK wrote: >>> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> JosephKK wrote: >>>>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> > <snip> >>>>> About 1/2 cubic inch any way you pack it. >>>> They aren't that big anymore. You can get X7R in 2220 but that size is >>>> already causing concern WRT stress fracture. >>>> >>> 1/2 cubic inch refers to film caps. Ceramic has not needed that much >>> volume for 4.7 uF for 20 years. >>>>> Alternatively i might try the aluminum polymer electrolytics. >>>> If I could get them in 2.5mm height or less. Plus there's the issue of >>>> freezing. >>> How would freezing affect a polymer (solid) electrolyte? ... >> >> That's what I don't know (yet). Unequal expansion in materials can cause >> seals to let go a bit, moisture gets in, and so on. Can't take a risk >> here and with the "responsiveness" of today's support lines I can't >> really wait. Layout is done now ;-) > > I suppose you could get some samples and play with temperature and voltage.
Well, it's done and done. We are well beyond the point of no return by now :-)
>> BTW, it's been almost a week now and AVX hasn't bothered to answer at >> all. It used to be such a great company. Anyone knows what happened? >> > IIRC they got bought up not too long ago.
Sad. That's when things often go downhill, and fast. [...] -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
On Thu, 01 Apr 2010 10:07:24 -0700, Joerg <invalid@invalid.invalid> wrote:

>JosephKK wrote: >> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> JosephKK wrote: >>>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>
<snip>
>>>> About 1/2 cubic inch any way you pack it. >>> >>> They aren't that big anymore. You can get X7R in 2220 but that size is >>> already causing concern WRT stress fracture. >>> >> 1/2 cubic inch refers to film caps. Ceramic has not needed that much >> volume for 4.7 uF for 20 years. >>>> Alternatively i might try the aluminum polymer electrolytics. >>> >>> If I could get them in 2.5mm height or less. Plus there's the issue of >>> freezing. >> >> How would freezing affect a polymer (solid) electrolyte? ... > > >That's what I don't know (yet). Unequal expansion in materials can cause >seals to let go a bit, moisture gets in, and so on. Can't take a risk >here and with the "responsiveness" of today's support lines I can't >really wait. Layout is done now ;-)
I suppose you could get some samples and play with temperature and voltage.
> >BTW, it's been almost a week now and AVX hasn't bothered to answer at >all. It used to be such a great company. Anyone knows what happened? >
IIRC they got bought up not too long ago.
> >> ... Height may be >> the issue. Perhaps you could end using 50 2.2 uF caps instead. > > >We might have to. Although 4.7uF X7S dropping to half capacitance would >be essentially the same then, except they are a bit less expensive.
JosephKK wrote:
> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: > >> JosephKK wrote: >>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> JosephKK wrote: >>>>> On Thu, 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> Jon Kirwan wrote: >>>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>>> <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> Jon Kirwan wrote: >>>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>>> >>>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>>> >>>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>>> >>>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>>> >>>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but that >>>>>>>>>> doesn't sound right. Anyone have a link to some hard data, with a graph >>>>>>>>>> in there and preferably no marketing hype? >>>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>>> >>>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>>> what else I read was right. >>>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>>> can't even come close to using them in integrators, from >>>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>>> what they are good for. >>>>>>> >>>>>> That's what I am needing them for :-) >>>>> That is relatively easy. Polystyrene, polyethylene, or >>>>> polyethylenterephthalate [PET / Mylar] are normal materials >>>>> of choice. Of course if you have atypical size constraints >>>>> you may have real difficulty obtaining any parts of reasonable >>>>> price. >>>> Atypical? A 4.7uF/100V film cap is going to be humongous. >>> About 1/2 cubic inch any way you pack it. >> >> They aren't that big anymore. You can get X7R in 2220 but that size is >> already causing concern WRT stress fracture. >> > 1/2 cubic inch refers to film caps. Ceramic has not needed that much > volume for 4.7 uF for 20 years. >>> Alternatively i might try the aluminum polymer electrolytics. >> >> If I could get them in 2.5mm height or less. Plus there's the issue of >> freezing. > > How would freezing affect a polymer (solid) electrolyte? ...
That's what I don't know (yet). Unequal expansion in materials can cause seals to let go a bit, moisture gets in, and so on. Can't take a risk here and with the "responsiveness" of today's support lines I can't really wait. Layout is done now ;-) BTW, it's been almost a week now and AVX hasn't bothered to answer at all. It used to be such a great company. Anyone knows what happened?
> ... Height may be > the issue. Perhaps you could end using 50 2.2 uF caps instead.
We might have to. Although 4.7uF X7S dropping to half capacitance would be essentially the same then, except they are a bit less expensive. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
On Tue, 30 Mar 2010 16:35:38 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Tue, 30 Mar 2010 16:00:32 -0700, Joerg <invalid@invalid.invalid> >wrote: > >>krw@att.bizzzzzzzzzzzz wrote: >>> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> JosephKK wrote: >>>>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> JosephKK wrote: >>>>>>> On Thu, 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> Jon Kirwan wrote: >>>>>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>> Jon Kirwan wrote: >>>>>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>> >>>>>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>>>>> >>>>>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>>>>> >>>>>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>>>>> >>>>>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>>>>> >>>>>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but that >>>>>>>>>>>> doesn't sound right. Anyone have a link to some hard data, with a graph >>>>>>>>>>>> in there and preferably no marketing hype? >>>>>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>>>>> >>>>>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>>>>> what else I read was right. >>>>>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>>>>> can't even come close to using them in integrators, from >>>>>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>>>>> what they are good for. >>>>>>>>> >>>>>>>> That's what I am needing them for :-) >>>>>>> That is relatively easy. Polystyrene, polyethylene, or >>>>>>> polyethylenterephthalate [PET / Mylar] are normal materials >>>>>>> of choice. Of course if you have atypical size constraints >>>>>>> you may have real difficulty obtaining any parts of reasonable >>>>>>> price. >>>>>> Atypical? A 4.7uF/100V film cap is going to be humongous. >>>>> About 1/2 cubic inch any way you pack it. >>>> >>>> They aren't that big anymore. You can get X7R in 2220 but that size is >>>> already causing concern WRT stress fracture. >>>> >>>> >>>>> Alternatively i might try the aluminum polymer electrolytics. >>>> >>>> If I could get them in 2.5mm height or less. Plus there's the issue of >>>> freezing. >>> >>> Freezing? Are your catheters used on Demonicrats too? What ever would they >>> be looking for? >> >> >>No, medical is not the only branch I am designing for. It's actually >>less and less medical which is sort of a good thing (can't get PL >>coverage because of that). Aerospace, industrial, harsh environment >>stuff, and so on. > >Can you get PL if it's only industrial? > >I find, as soon as you say "computer", the insurance companies run for >cover. I don't understand why. > > ...Jim Thompson
In a brand name, "Microsoft".
On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote:

>JosephKK wrote: >> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> JosephKK wrote: >>>> On Thu, 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> Jon Kirwan wrote: >>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>> <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> Jon Kirwan wrote: >>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>> >>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>> >>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>> >>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>> >>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>> >>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but that >>>>>>>>> doesn't sound right. Anyone have a link to some hard data, with a graph >>>>>>>>> in there and preferably no marketing hype? >>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>> >>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>> what else I read was right. >>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>> can't even come close to using them in integrators, from >>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>> what they are good for. >>>>>> >>>>> That's what I am needing them for :-) >>>> That is relatively easy. Polystyrene, polyethylene, or >>>> polyethylenterephthalate [PET / Mylar] are normal materials >>>> of choice. Of course if you have atypical size constraints >>>> you may have real difficulty obtaining any parts of reasonable >>>> price. >>> >>> Atypical? A 4.7uF/100V film cap is going to be humongous. >> >> About 1/2 cubic inch any way you pack it. > > >They aren't that big anymore. You can get X7R in 2220 but that size is >already causing concern WRT stress fracture. >
1/2 cubic inch refers to film caps. Ceramic has not needed that much volume for 4.7 uF for 20 years.
> >> Alternatively i might try the aluminum polymer electrolytics. > > >If I could get them in 2.5mm height or less. Plus there's the issue of >freezing.
How would freezing affect a polymer (solid) electrolyte? Height may be the issue. Perhaps you could end using 50 2.2 uF caps instead.
On Tue, 30 Mar 2010 04:03:51 +0000 (UTC), don@manx.misty.com (Don Klipstein) wrote:

>In article <pbq2r515863lg09qmpdnohacscu1ntrnk5@4ax.com>, JosephKK wrote: >>On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>>JosephKK wrote: >>>> On 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> Jon Kirwan wrote: >>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>> <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> Jon Kirwan wrote: >>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>> >>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>> >>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>> >>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>> >>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>> >>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but >>>>>>>>> that doesn't sound right. Anyone have a link to some hard data, >>>>>>>>> with a graph in there and preferably no marketing hype? >>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>> >>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>> what else I read was right. >>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>> can't even come close to using them in integrators, from >>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>> what they are good for. >>>>>> >>>>> That's what I am needing them for :-) >>>> >>>> That is relatively easy. Polystyrene, polyethylene, or >>>> polyethylenterephthalate [PET / Mylar] are normal materials of >>>> choice. Of course if you have atypical size constraints you may >>>> have real difficulty obtaining any parts of reasonable price. >>> >>>Atypical? A 4.7uF/100V film cap is going to be humongous. >> >>About 1/2 cubic inch any way you pack it. >>Alternatively i might try the aluminum polymer electrolytics. > > "Electrolytic" makes an alarm bell go off in my head against >expectation of capacitance refusing to vary with voltage. > > Is there a reason for polymer to fix this for aluminum electrolytics? > > - Don Klipstein (don@misty.com)
No, but if i read the datasheets correctly it is less than the MLCs with comparable volumetric charge density.
Jim Thompson wrote:
> On Tue, 30 Mar 2010 16:00:32 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> krw@att.bizzzzzzzzzzzz wrote: >>> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> JosephKK wrote: >>>>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> JosephKK wrote: >>>>>>> On Thu, 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> Jon Kirwan wrote: >>>>>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>> Jon Kirwan wrote: >>>>>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>> >>>>>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>>>>> >>>>>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>>>>> >>>>>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>>>>> >>>>>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>>>>> >>>>>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but that >>>>>>>>>>>> doesn't sound right. Anyone have a link to some hard data, with a graph >>>>>>>>>>>> in there and preferably no marketing hype? >>>>>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>>>>> >>>>>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>>>>> what else I read was right. >>>>>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>>>>> can't even come close to using them in integrators, from >>>>>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>>>>> what they are good for. >>>>>>>>> >>>>>>>> That's what I am needing them for :-) >>>>>>> That is relatively easy. Polystyrene, polyethylene, or >>>>>>> polyethylenterephthalate [PET / Mylar] are normal materials >>>>>>> of choice. Of course if you have atypical size constraints >>>>>>> you may have real difficulty obtaining any parts of reasonable >>>>>>> price. >>>>>> Atypical? A 4.7uF/100V film cap is going to be humongous. >>>>> About 1/2 cubic inch any way you pack it. >>>> They aren't that big anymore. You can get X7R in 2220 but that size is >>>> already causing concern WRT stress fracture. >>>> >>>> >>>>> Alternatively i might try the aluminum polymer electrolytics. >>>> If I could get them in 2.5mm height or less. Plus there's the issue of >>>> freezing. >>> Freezing? Are your catheters used on Demonicrats too? What ever would they >>> be looking for? >> >> No, medical is not the only branch I am designing for. It's actually >> less and less medical which is sort of a good thing (can't get PL >> coverage because of that). Aerospace, industrial, harsh environment >> stuff, and so on. > > Can you get PL if it's only industrial? >
AFAICT yes. But if the box "Do you design medical electronics?" is checked you are instantly a pariah.
> I find, as soon as you say "computer", the insurance companies run for > cover. I don't understand why. >
They like to only insure underwater carpet fires. Heck, they even exclude recalls which makes the whole PL concept pointless for anyone who designs products. I mean, what are they thinking that engineers do? Research in some ivory tower all day long and write nice papers in LaTex? A chat with an underwriter a few years ago: "So you design products, huh?" ... "Yeah." ... "So how long do they typically remain in production?" ... "Oh, 10, 15 years." ... *THUD* -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
On Tue, 30 Mar 2010 16:00:32 -0700, Joerg <invalid@invalid.invalid>
wrote:

>krw@att.bizzzzzzzzzzzz wrote: >> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> JosephKK wrote: >>>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> JosephKK wrote: >>>>>> On Thu, 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> Jon Kirwan wrote: >>>>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>> >>>>>>>>> Jon Kirwan wrote: >>>>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>> >>>>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>>>> >>>>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>>>> >>>>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>>>> >>>>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>>>> >>>>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but that >>>>>>>>>>> doesn't sound right. Anyone have a link to some hard data, with a graph >>>>>>>>>>> in there and preferably no marketing hype? >>>>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>>>> >>>>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>>>> what else I read was right. >>>>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>>>> can't even come close to using them in integrators, from >>>>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>>>> what they are good for. >>>>>>>> >>>>>>> That's what I am needing them for :-) >>>>>> That is relatively easy. Polystyrene, polyethylene, or >>>>>> polyethylenterephthalate [PET / Mylar] are normal materials >>>>>> of choice. Of course if you have atypical size constraints >>>>>> you may have real difficulty obtaining any parts of reasonable >>>>>> price. >>>>> Atypical? A 4.7uF/100V film cap is going to be humongous. >>>> About 1/2 cubic inch any way you pack it. >>> >>> They aren't that big anymore. You can get X7R in 2220 but that size is >>> already causing concern WRT stress fracture. >>> >>> >>>> Alternatively i might try the aluminum polymer electrolytics. >>> >>> If I could get them in 2.5mm height or less. Plus there's the issue of >>> freezing. >> >> Freezing? Are your catheters used on Demonicrats too? What ever would they >> be looking for? > > >No, medical is not the only branch I am designing for. It's actually >less and less medical which is sort of a good thing (can't get PL >coverage because of that). Aerospace, industrial, harsh environment >stuff, and so on.
Can you get PL if it's only industrial? I find, as soon as you say "computer", the insurance companies run for cover. I don't understand why. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
On Tue, 30 Mar 2010 16:00:32 -0700, Joerg <invalid@invalid.invalid> wrote:

>krw@att.bizzzzzzzzzzzz wrote: >> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> JosephKK wrote: >>>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>>> >>>>> JosephKK wrote: >>>>>> On Thu, 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> Jon Kirwan wrote: >>>>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>> >>>>>>>>> Jon Kirwan wrote: >>>>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>> >>>>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>>>> >>>>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>>>> >>>>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>>>> >>>>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>>>> >>>>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but that >>>>>>>>>>> doesn't sound right. Anyone have a link to some hard data, with a graph >>>>>>>>>>> in there and preferably no marketing hype? >>>>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>>>> >>>>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>>>> what else I read was right. >>>>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>>>> can't even come close to using them in integrators, from >>>>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>>>> what they are good for. >>>>>>>> >>>>>>> That's what I am needing them for :-) >>>>>> That is relatively easy. Polystyrene, polyethylene, or >>>>>> polyethylenterephthalate [PET / Mylar] are normal materials >>>>>> of choice. Of course if you have atypical size constraints >>>>>> you may have real difficulty obtaining any parts of reasonable >>>>>> price. >>>>> Atypical? A 4.7uF/100V film cap is going to be humongous. >>>> About 1/2 cubic inch any way you pack it. >>> >>> They aren't that big anymore. You can get X7R in 2220 but that size is >>> already causing concern WRT stress fracture. >>> >>> >>>> Alternatively i might try the aluminum polymer electrolytics. >>> >>> If I could get them in 2.5mm height or less. Plus there's the issue of >>> freezing. >> >> Freezing? Are your catheters used on Demonicrats too? What ever would they >> be looking for? > > >No, medical is not the only branch I am designing for. It's actually >less and less medical which is sort of a good thing (can't get PL >coverage because of that). Aerospace, industrial, harsh environment >stuff, and so on.
You had me wondering there. ;-)
krw@att.bizzzzzzzzzzzz wrote:
> On Tue, 30 Mar 2010 09:03:17 -0700, Joerg <invalid@invalid.invalid> wrote: > >> JosephKK wrote: >>> On Sun, 28 Mar 2010 13:47:48 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> JosephKK wrote: >>>>> On Thu, 25 Mar 2010 08:05:08 -0700, Joerg <invalid@invalid.invalid> wrote: >>>>> >>>>>> Jon Kirwan wrote: >>>>>>> On Wed, 24 Mar 2010 17:41:39 -0700, Joerg >>>>>>> <invalid@invalid.invalid> wrote: >>>>>>> >>>>>>>> Jon Kirwan wrote: >>>>>>>>> On Wed, 24 Mar 2010 16:22:59 -0700, Joerg >>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>> >>>>>>>>>> Tried the major mfgs and the typical datasheet looks like this: >>>>>>>>>> >>>>>>>>>> http://www.avx.com/docs/Catalogs/cx7s.pdf >>>>>>>>>> >>>>>>>>>> Quote "Capacitance for X7S varies under the influence of electrical >>>>>>>>>> operating conditions such as voltage and frequency." >>>>>>>>>> >>>>>>>>>> Then under diagrams ... nada, zip, zilch. Great. >>>>>>>>>> >>>>>>>>>> One paper listed X7S with the same voltage coefficient as X7R but that >>>>>>>>>> doesn't sound right. Anyone have a link to some hard data, with a graph >>>>>>>>>> in there and preferably no marketing hype? >>>>>>>>> I seem to recall reading that C0G and NP0 dielectrics have >>>>>>>>> the lowest cap-vs-temp dependance and that pretty much >>>>>>>>> everyone "understands" that X7R dielectrics have large >>>>>>>>> coefficients and are pretty much unsuitable where it matters. >>>>>>>>> They pack a lot of capacitance into a small space and that >>>>>>>>> makes them great for decoupling jobs and not so much else. >>>>>>>>> >>>>>>>>> But I don't know remember reading anything about X7S, >>>>>>>>> specifically. If they are the same as X7R, they are crap if >>>>>>>>> what else I read was right. >>>>>>>> The lousy ones are Y5V and Z5U. X7R is actually pretty good. >>>>>>> X7R is bad enough that it distorts like hell in an audio >>>>>>> amplifier (used as the Miller cap) and I know I certainly >>>>>>> can't even come close to using them in integrators, from >>>>>>> actual (hilarious, for a moment) experience. Decoupling is >>>>>>> what they are good for. >>>>>>> >>>>>> That's what I am needing them for :-) >>>>> That is relatively easy. Polystyrene, polyethylene, or >>>>> polyethylenterephthalate [PET / Mylar] are normal materials >>>>> of choice. Of course if you have atypical size constraints >>>>> you may have real difficulty obtaining any parts of reasonable >>>>> price. >>>> Atypical? A 4.7uF/100V film cap is going to be humongous. >>> About 1/2 cubic inch any way you pack it. >> >> They aren't that big anymore. You can get X7R in 2220 but that size is >> already causing concern WRT stress fracture. >> >> >>> Alternatively i might try the aluminum polymer electrolytics. >> >> If I could get them in 2.5mm height or less. Plus there's the issue of >> freezing. > > Freezing? Are your catheters used on Demonicrats too? What ever would they > be looking for?
No, medical is not the only branch I am designing for. It's actually less and less medical which is sort of a good thing (can't get PL coverage because of that). Aerospace, industrial, harsh environment stuff, and so on. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.