Quick ESR answer needed
Jim Thompson
Typical 0.22uF ceramic in low voltage application (5V max), what ESR
might I expect?
Client says 0.2 Ohms
I doubt that number, but don't have anything to base my doubt on.
What say yee all?
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
Kevin Aylward
> Quick ESR answer needed...
>
> Typical 0.22uF ceramic in low voltage application (5V max), what ESR
> might I expect?
>
> Client says 0.2 Ohms
>
> I doubt that number, but don't have anything to base my doubt on.
>
> What say yee all?
Ceramic, I say in the 10m to 50m range.
--
Kevin Aylward
k...@kevinaylward.co.uk
Tom Bruhns
What _kind_ of ceramic?? Kemet's data sheet for ceramic SMT caps
suggests that the ESR of X5R caps in the 0.1uF to 1.0uF range is under
0.01 ohms. That applies to 0603 through 1206 sizes. But the ESR
varies with dielectric in their data sheet, and I'm sure it varies
with manufacturer. Kemet, for example, suggests an ESR in the 0.1 ohm
region for Z5U and Y5V parts. "YMMV" What I say, bottom line, is
start with manufacturers' data sheets for the particular parts in
question, and if you have reason to suspect they aren't accurate,
MEASURE it.
Cheers,
Tom
Tim Shoppa
Web-Site.com> wrote:
> Quick ESR answer needed...
>
> Typical 0.22uF ceramic in low voltage application (5V max), what ESR
> might I expect?
>
> Client says 0.2 Ohms
>
> I doubt that number, but don't have anything to base my doubt on.
>
> What say yee all?
The low-uF ceramic chips with X7R dielectric often have an ESR of 0.02
ohms or so in the 50kHz to 500kHz range.
Some 100uF 6.3V Y5V ceramic chips spec as low as as 0.002 ohms over
the same frequency range.
A couple of the LDO regulator app notes warn that the devices may not
be stable with low-ESR caps on their output and in fact show resistors
in series with such caps!
Tim.
Joerg
> Quick ESR answer needed...
>
> Typical 0.22uF ceramic in low voltage application (5V max), what ESR
> might I expect?
>
> Client says 0.2 Ohms
>
> I doubt that number, but don't have anything to base my doubt on.
>
> What say yee all?
>
Much lower IME, more in the range Kevin gave but it depends on the
frequency. I guess your client would want a somewhat more "official"
story about it, so here goes (the MLC versus Tantalum shoot-out):
http://www.avxcorp.com/docs/techinfo/mlc-tant.pdf
Ahem, you wouldn't think about counting on the ESR for a loop design,
would ya? No, can't be ....
--
Regards, Joerg
Lynn Richardson
<To-Email-Use-Th...@My-Web-Site.com> wrote:
>Quick ESR answer needed...
>
>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>might I expect?
>
>Client says 0.2 Ohms
>
>I doubt that number, but don't have anything to base my doubt on.
>
>What say yee all?
>
> ...Jim Thompson
Sounds about right for a Z5U dielectric low volt cap. These things are the pits.
Terrible temp and voltage curves with lots of microphonics and absorbtion. All
they are 'good' for is power filtering at the vcc terminals of ICs.
John Larkin
Bet he's designing a chip with built-in LDO!
I like the National AnyCap idea, an internal dominant pole that's
merely increased by external capacitance, not cascaded with it.
Basically, it's Miller capacitance off the output pin.
John
Joerg
> On Tue, 14 Aug 2007 10:41:32 -0700, Joerg
> <notthis...@removethispacbell.net> wrote:
>
>
>>Jim Thompson wrote:
>>
>>
>>>Quick ESR answer needed...
>>>
>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>might I expect?
>>>
>>>Client says 0.2 Ohms
>>>
>>>I doubt that number, but don't have anything to base my doubt on.
>>>
>>>What say yee all?
>>>
>>
>>Much lower IME, more in the range Kevin gave but it depends on the
>>frequency. I guess your client would want a somewhat more "official"
>>story about it, so here goes (the MLC versus Tantalum shoot-out):
>>
>>http://www.avxcorp.com/docs/techinfo/mlc-tant.pdf
>>
>>Ahem, you wouldn't think about counting on the ESR for a loop design,
>>would ya? No, can't be ....
>
>
> Bet he's designing a chip with built-in LDO!
>
Sounds like as much fun as repairing a dry-rot problem.
> I like the National AnyCap idea, an internal dominant pole that's
> merely increased by external capacitance, not cascaded with it.
> Basically, it's Miller capacitance off the output pin.
>
I think that's Analog Devices. Anyhow, yes, you can buy good LDOs but
for the privilege of having one that doesn't throw the occasional
tantrum you have to pay extra. "Oh, you want a car that doesn't have a
wobble at 65mph? Ok, but it'll cost ya."
As far as I am concerned I avoid LDOs like the plague.
PeteS
> Quick ESR answer needed...
>
> Typical 0.22uF ceramic in low voltage application (5V max), what ESR
> might I expect?
>
> Client says 0.2 Ohms
>
> I doubt that number, but don't have anything to base my doubt on.
>
> What say yee all?
>
> ...Jim Thompson
2 milliohm is reasonable provided the device is rated at 10V. If it's
rated at 6V, then figure about 10 milliohm.
Cheers
PeteS
PeteS
Cheers
PeteS
john jardine
"PeteS" <axk...@dsl.pipex.com> wrote in message
news:IcSdncGmicnHYVzb...@pipex.net...
Just measured one to hand.
100nF, Y5V, 25kHz, 5ohm.
1kHz 55ohm.
(for comparison, a 100nF poly' gave 8ohm at 1kHz)
Looks like I always end up at the cheap tat end of the market :)
PeteS
my numbers from. The cheaper stuff will always have worse numbers, of
course ;)
Cheers
PeteS
John Larkin
Those numbers seem extreme, high by 2 or 3 orders of magnitude. How
did you measure them?
John
Jim Thompson
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>On Tue, 14 Aug 2007 10:41:32 -0700, Joerg
><notthis...@removethispacbell.net> wrote:
>
>>Jim Thompson wrote:
>>
>>> Quick ESR answer needed...
>>>
>>> Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>> might I expect?
>>>
>>> Client says 0.2 Ohms
>>>
>>> I doubt that number, but don't have anything to base my doubt on.
>>>
>>> What say yee all?
>>>
>>
>>Much lower IME, more in the range Kevin gave but it depends on the
>>frequency. I guess your client would want a somewhat more "official"
>>story about it, so here goes (the MLC versus Tantalum shoot-out):
>>
>>http://www.avxcorp.com/docs/techinfo/mlc-tant.pdf
>>
>>Ahem, you wouldn't think about counting on the ESR for a loop design,
>>would ya? No, can't be ....
>
>Bet he's designing a chip with built-in LDO!
Nope. Dumping said capacitor into a 1.5 Ohm load using a PMOS/NMOS
totem pole that uses up 1/3 of the chip :-(
>
>I like the National AnyCap idea, an internal dominant pole that's
>merely increased by external capacitance, not cascaded with it.
>Basically, it's Miller capacitance off the output pin.
>
>John
>
>
...Jim Thompson
Joerg
> On Tue, 14 Aug 2007 11:27:24 -0700, John Larkin
> <jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>
>
>>On Tue, 14 Aug 2007 10:41:32 -0700, Joerg
>><notthis...@removethispacbell.net> wrote:
>>
>>
>>>Jim Thompson wrote:
>>>
>>>
>>>>Quick ESR answer needed...
>>>>
>>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>>might I expect?
>>>>
>>>>Client says 0.2 Ohms
>>>>
>>>>I doubt that number, but don't have anything to base my doubt on.
>>>>
>>>>What say yee all?
>>>>
>>>
>>>Much lower IME, more in the range Kevin gave but it depends on the
>>>frequency. I guess your client would want a somewhat more "official"
>>>story about it, so here goes (the MLC versus Tantalum shoot-out):
>>>
>>>http://www.avxcorp.com/docs/techinfo/mlc-tant.pdf
>>>
>>>Ahem, you wouldn't think about counting on the ESR for a loop design,
>>>would ya? No, can't be ....
>>
>>Bet he's designing a chip with built-in LDO!
>
>
> Nope. Dumping said capacitor into a 1.5 Ohm load using a PMOS/NMOS
> totem pole that uses up 1/3 of the chip :-(
>
Hopefully this one can run on a cheap process then.
>
>>I like the National AnyCap idea, an internal dominant pole that's
>>merely increased by external capacitance, not cascaded with it.
>>Basically, it's Miller capacitance off the output pin.
>>
--
Regards, Joerg
Phil Allison
"John Larkin"
"john jardine"
>>
>>Just measured one to hand.
>>100nF, Y5V, 25kHz, 5ohm.
>> 1kHz 55ohm.
>>(for comparison, a 100nF poly' gave 8ohm at 1kHz)
>>
>
> Those numbers seem extreme, high by 2 or 3 orders of magnitude. How
> did you measure them?
** With one of these maybe ?
http://www.m3electronix.com/featureslcr.html
Told us he owned one back on July 17.
God knows how he got those mad results.
....... Phil
john jardine
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
news:lb44c3lug2218vo5p...@4ax.com...
Measured on a bit of kit I bought last week.
http://www.mwinstruments.com/MW1008/MW1008_f.html
Cheap but very handy. It measures the component impedance and VI phase
displacement. All other secondary components such as LCR are then derived
mathematically.
Just for comparison I checked a part I can trace. It's a 470n open frame
Polyester, EPCOS part #B32560J1474K. The data sheet states a loss factor of
0.008 at 1kHz.
The meter (test at 1kHz) shows D=0.0046, L=475.6nF, Series R=1.55ohms.
The values tie up nicely.
(Had assumed most people would be equipped with fancy HP analyzers and would
have posted a measurement or two but haven't see anything come in yet.)
John Larkin
<john.j...@idnet.co.uk> wrote:
All those numbers sound very weird to me. And you can't calculate ESR
from a single-frequency vector impedance measurement. The polyester
loss is most likely dielectric absorption, which does not translate to
esr.
I just measured an axial-lead 0.1 uF ceramic cap directly, by applying
a current pulse and observing the voltage waveform. It's showing about
50 milliohms, but that's close to my resolution limit.
John
Joerg
And it isn't necessarily linear either. When I was a kid I thought I had
it all figured out with RF power stuff. Measured the ESR of a largish
cap at 21MHz, the frequency where I needed it. Assumed it would remain
constant regardless of current level. Yeah, right. Calculated the
dissipation this would cause, lots of margin, nothing would get hot
here. Or so I thought. Soldered it in place and about five minutes into
using it ... KABLOUIE! Molten stuff all over the place.
BTW, just curious, does your TDS2024 also lack delayed trigger? My
Instek 2204 does, and so do lots of others. Shook my head when I found out.
Phil Allison
"john jardine"
>
> Just for comparison I checked a part I can trace. It's a 470n open frame
> Polyester, EPCOS part #B32560J1474K. The data sheet states a loss factor
> of
> 0.008 at 1kHz.
> The meter (test at 1kHz) shows D=0.0046, L=475.6nF, Series R=1.55ohms.
> The values tie up nicely.
>
** The published data for that same cap shows it has an impedance minimum at
just over 3 MHz of 33 milliohms.
........ Phil
John Larkin
<notthis...@removethispacbell.net> wrote:
>John Larkin wrote:
>
>> On Tue, 14 Aug 2007 10:41:32 -0700, Joerg
>> <notthis...@removethispacbell.net> wrote:
>>
>>
>>>Jim Thompson wrote:
>>>
>>>
>>>>Quick ESR answer needed...
>>>>
>>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>>might I expect?
>>>>
>>>>Client says 0.2 Ohms
>>>>
>>>>I doubt that number, but don't have anything to base my doubt on.
>>>>
>>>>What say yee all?
>>>>
>>>
>>>Much lower IME, more in the range Kevin gave but it depends on the
>>>frequency. I guess your client would want a somewhat more "official"
>>>story about it, so here goes (the MLC versus Tantalum shoot-out):
>>>
>>>http://www.avxcorp.com/docs/techinfo/mlc-tant.pdf
>>>
>>>Ahem, you wouldn't think about counting on the ESR for a loop design,
>>>would ya? No, can't be ....
>>
>>
>> Bet he's designing a chip with built-in LDO!
>>
>
>Sounds like as much fun as repairing a dry-rot problem.
>
>
>> I like the National AnyCap idea, an internal dominant pole that's
>> merely increased by external capacitance, not cascaded with it.
>> Basically, it's Miller capacitance off the output pin.
>>
>
>I think that's Analog Devices.
Yeah, I was thinking of the National C-load opamps, like the LM8261.
John
John Larkin
No delayed trigger, and only as much memory as fills the screen. We
have a bigger one, 500 MHz, forget the model number, that has more
memory and delay.
John
Steve Wolfe
> suggests that the ESR of X5R caps in the 0.1uF to 1.0uF range is under
> 0.01 ohms. That applies to 0603 through 1206 sizes. But the ESR
> varies with dielectric in their data sheet, and I'm sure it varies
> with manufacturer.
Might I ask to which data sheet you refer? I have looked through Kemet's
site, and haven't been able to find ESR figures for their SMT ceramic caps.
steve
Tom Bruhns
The key it the "suggests" word in my posting above. It's from my
reading of the graphs of |impedance| versus frequency; the minimum I
assume to be where the capacitive and inductive reactances balance and
you're left looking at the esr at that frequency. It's not guaranteed
to be the same as a DC esr, of course. (Or maybe I should say is
guaranteed to not be...) The particular sheet is a pdf that covers
C0G, X5R, Y5V and one or two others.
Cheers,
Tom
The Phantom
<To-Email-Use-Th...@My-Web-Site.com> wrote:
>Quick ESR answer needed...
>
>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>might I expect?
At what frequency? That makes a big difference.
Phil Allison
"The Phantom"
Jim Thompson
>>
>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>might I expect?
>
> At what frequency? That makes a big difference.
** Not to the minimum impedance the cap can exhibit - which is the series
resistance that counts for supply bypass and filtering applications.
No one is too bothered about di-electric losses for that as they only help !
....... Phil
The Phantom
I would definitely say it's guaranteed not to be.
I measured a .27 uF SMT part (I don't know the dielectric). It has an
ESR of 40 milliohms up around 1 MHz. The ESR at 100 Hz is 180 ohms, and at
20 Hz it's about 800 ohms. It varies with applied voltage, so it must not
be COG; it's one of those dielectrics giving a capacitance that varies with
applied voltage.
How would you define (and measure) DC ESR?
>The particular sheet is a pdf that covers
>C0G, X5R, Y5V and one or two others.
Data sheet found at:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/B3D6942FD742E4A5CA2570A500160908/$file/F3102_CerPerChar.pdf
>
>Cheers,
>Tom
Joerg
Why on earth didn't they provide delayed trigger? It's so easy ....
<banging head on table>
In single channel the TDS2024 should yield about five times the screen.
But that ain't enough for me which is one reason why I bought the Instek
(has 25K memory). At least that gets me to 25usec single channel. Still
drooling over the 1M or so of the Hameg 2008 but it's just too large in
size.
John Devereux
> On Tue, 14 Aug 2007 22:16:39 -0700, Tom Bruhns <k7...@msn.com> wrote:
>
>>On Aug 14, 9:55 pm, "Steve Wolfe" <h...@codon.com> wrote:
>>> > What _kind_ of ceramic?? Kemet's data sheet for ceramic SMT caps
>>> > suggests that the ESR of X5R caps in the 0.1uF to 1.0uF range is under
>>> > 0.01 ohms. That applies to 0603 through 1206 sizes. But the ESR
>>> > varies with dielectric in their data sheet, and I'm sure it varies
>>> > with manufacturer.
>>>
>>> Might I ask to which data sheet you refer? I have looked through Kemet's
>>> site, and haven't been able to find ESR figures for their SMT ceramic caps.
>>>
>>> steve
>>
>>The key it the "suggests" word in my posting above. It's from my
>>reading of the graphs of |impedance| versus frequency; the minimum I
>>assume to be where the capacitive and inductive reactances balance and
>>you're left looking at the esr at that frequency. It's not guaranteed
>>to be the same as a DC esr, of course. (Or maybe I should say is
>>guaranteed to not be...)
That's the way I have looked at it too.
> I would definitely say it's guaranteed not to be.
>
> I measured a .27 uF SMT part (I don't know the dielectric). It has an
> ESR of 40 milliohms up around 1 MHz. The ESR at 100 Hz is 180 ohms, and at
> 20 Hz it's about 800 ohms. It varies with applied voltage, so it must not
> be COG; it's one of those dielectrics giving a capacitance that varies with
> applied voltage.
I don't see how such high values are possible - how are you measuring
them? I can see how the ESR might vary with frequency, but the
mechanisms I can think of would all produce an ESR that *increased*
with frequency (like with inductor losses, e.g. skin effect).
> How would you define (and measure) DC ESR?
Perhaps you could define it as the limit as the frequency tends to
zero. It *ought* to be flat there anyway, so should be identical at
10kHz, 1kHz etc.
>
>>The particular sheet is a pdf that covers
>>C0G, X5R, Y5V and one or two others.
>
> Data sheet found at:
> http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/B3D6942FD742E4A5CA2570A500160908/$file/F3102_CerPerChar.pdf
>
>>
>>Cheers,
>>Tom
>
--
John Devereux
Steve Wolfe
>> Kemet's
>> site, and haven't been able to find ESR figures for their SMT ceramic
>> caps.
>>
> reading of the graphs of |impedance| versus frequency; the minimum I
> assume to be where the capacitive and inductive reactances balance and
> you're left looking at the esr at that frequency.
Ah. Gotcha. I bought a bunch of new, in-the-tape .22 uF Kemet X7R caps
for what seemed to be a more-or-less ordinary price, figuring I'd use them
for decoupling caps. I hadn't looked at the small print, they turned out to
be 100V, 1825-size caps. Mouser has them at $1.44 in quantities of 1,000, I
picked mine up for four cents each.
When I saw how large they were, I got to wondering about the ESR of an
1825-sized cap vs. 0805 or 1206. I figure between a greater capacitance
than the "standard" 0.1uF, and a lower ESR (presumably), they should work
very well. But, because of the size, I have yet to use any of them. Ah,
well. :-)
steve
jeroen....@cern.ch
> I measured a .27 uF SMT part (I don't know the dielectric). It has anESRof 40 milliohms up around 1 MHz. TheESRat 100 Hz is 180 ohms, and at
> 20 Hz it's about 800 ohms. It varies with applied voltage, so it must not
> be COG; it's one of those dielectrics giving a capacitance that varies with
> applied voltage.
>From those numbers, I'd say you have exceeded the capabilities of your
measuring instrument. Apparently it cannot resolve a real part less
than about 1/30th of the imaginary part of the impedance.
Jeroen Belleman/CERN
John Devereux
They may have a lower *ESR*, but for many applications
(e.g. decoupling) what matters is the total impedance, which is often
dominated by ESL (inductance). This is usually lower with *smaller*
devices.
--
John Devereux
The Phantom
I'm measuring them with a Wayne-Kerr component analyzer. The high
numbers are an artifact of using a series model rather than a parallel
model, which would probably be more appropriate at low frequencies.
Consider the admittance of a .27 uF capacitor (at 20 Hz) in parallel with
1 megohm (due to dielectric loss).
The total admittance would be .000001 + j .0000339292
Take the reciprocal to convert admittance to impedance and get:
867.0 - j 29447.558
that is, 867 ohms in series with a ~ .27 uF capacitor.
Start out with 10 megohms in parallel:
.0000001 + j .0000339292, and reciprocate:
86.9 - j 29472.9
that is, 86.9 ohms in series with a ~.27 uF capacitor, etc.
A more accurate model would assume a parallel resistance to represent the
dielectric losses, and a small series resistance to represent the current
in metallization and leads (if any) losses.
The higher the EPR (equivalent parallel resistance), the lower the ESR
(equivalent series resistance) at a given frequency of measurement. The
ESR is a representation of all the losses as a series resistance.
A constant 1 megohm resistance in parallel with the admittance of a .27
uF capacitor will convert to a higher and higher series resistance as the
frequency goes lower and lower. The parallel loss resistance of a
capacitor isn't truly constant with decreasing frequency, but you get the
idea. This is why the ESR of capacitors increases as you go to low audio
frequencies.
The Phantom
Actually the instrument can easily resolve a real part less than 1/1000th
of the imaginary part. See my response to John Devereux.
>
>Jeroen Belleman/CERN
Fred Bartoli
Absolutely not. You totally miss the point about *equivalent* series
resistance, which is the value needed for a not physically based
equivalent circuit (but easy to understand) to behave like the real cap.
This esr, as you know, models losses. Dielectric, conduction, and maybe,
ahem, radiative losses too.
The minimum impedance at resonance is often dominated by conduction
losses, which is the *true* serial resistance. (notice I didn't used the
term 'equivalent').
For ex. a 100nF with a 1nH esl will resonate at 100Mrd/s (16MHz) giving
Zc=0.1R
With a bad 5% dielectric loss, that's only 5mR additionnal resistance. So
a cap showing 20-30mR *esr* at its resonance frequency has this
resistance to be dominated by conduction losses.
Obviously, as you noted, these conduction losses will increase with
frequency due to skin and proximity effects (don't we want electrodes to
be close to each other in a cap?).
Now, for the *e*sr value at low frequency, you have the dissipation
factor DF = Zc/esr = 1/(C.w.esr) or esr=1/(C.w.DF)
DF being very roughly constant over frequency, you can see that the *e*sr
has to rise at low frequency.
Again *e*sr isn't a true series resistance.
--
Thanks,
Fred.
Fred Bartoli
This should obviously have been:
Now, for the *e*sr value at low frequency, you have the dissipation
factor DF = esr/Zc = C.w.esr or esr=DF/(C.w) DF being very roughly
John Devereux
> Le Wed, 15 Aug 2007 08:58:26 +0100, John Devereux a écrit:
>
>> The Phantom <pha...@aol.com> writes:
[...]
Thanks to Fred and the phantom for the explanations - new information
for me I have to admit!
--
John Devereux
Jim Thompson
wrote:
If frequency makes a difference then isn't it "ESL" rather than ESR?
Application has capacitor charged to +1.8V, it is then connected (4ns
full-on connect time) thru a 1.5 Ohm "strap" to -1.8V.
In other words, over 2A peak current.
John Larkin
wrote:
>On Wed, 15 Aug 2007 08:58:26 +0100, John Devereux
Flipping shunt losses mathematically to compute ESR is a very poor
model. If one is doing pulse discharge, or hf bypassing, or
stabilizing a regulator, such huge ESRs are total nonsense.
You can of course measure the losses of a ceramic chip cap at 20 Hz
and decide the "equivalent" series resistance is 800 ohms, but that is
a bit deceptive when the actual series resistance is several thousand
times lower.
A better model is
---------+
|
L1
|
|
R1
|
+--------+----- etc, if you're
| | compulsive
C1 C2
| |
| |
| R2
| |
| |
---------+--------+------
which has more information than just two numbers.
John
The Phantom
The Phantom
ESR is not "actual series resistance". There's a reason it's called
"equivalent" series resistance. It's not a model that can be used to
*calculate* the impedance versus frequency, as with the schematic you've
shown below. Your model has resistors that don't vary with frequency; the
ESR model used by the cap manufacturers has an "equivalent" series
resistance that varies with frequency, and its value at any given frequency
is found by measurement at that frequency. It's just the real part of the
impedance as measured, and represents all the losses at that frequency as a
single "equivalent" series resistance.
See: http://en.wikipedia.org/wiki/Equivalent_series_resistance
>
>A better model is
>
>
>
>---------+
> |
> L1
> |
> |
> R1
> |
> +--------+----- etc, if you're
> | | compulsive
> C1 C2
> | |
> | |
> | R2
> | |
> | |
>---------+--------+------
>
>
>which has more information than just two numbers.
Indeed it does, but this isn't what is meant by manufacturers when they
talk about ESR. If you measure the impedance of a capacitor at some
frequency, the real part of the impedance won't be what you have shown as
R1 if there are any other losses, which there usually are.
I now see why you said "...you can't calculate ESR
from a single-frequency vector impedance measurement."
This would be true if ESR (as used by the manufacturers of capacitors)
were R1 in your schematic, but that isn't what they mean by the term.
>
>
>John
>
The Phantom
<To-Email-Use-Th...@My-Web-Site.com> wrote:
>On Tue, 14 Aug 2007 23:42:47 -0700, The Phantom <pha...@aol.com>
>wrote:
>
>>On Tue, 14 Aug 2007 09:51:38 -0700, Jim Thompson
>><To-Email-Use-Th...@My-Web-Site.com> wrote:
>>
>>>Quick ESR answer needed...
>>>
>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>might I expect?
>>
>> At what frequency? That makes a big difference.
>>
>>>
>>>Client says 0.2 Ohms
>>>
>>>I doubt that number, but don't have anything to base my doubt on.
>>>
>>>What say yee all?
>>>
>>> ...Jim Thompson
>
>If frequency makes a difference then isn't it "ESL" rather than ESR?
ESR (with the meaning as used by the capacitor manufacturers) does vary
with frequency. See: http://www.avxcorp.com/docs/techinfo/mlc-tant.pdf
Of course, capacitors have an ESL as well as an ESR (the E stands for
Equivalent, which means a simple model), and the *impedance* of the
capacitor is dominated by ESL above the series resonant frequency.
The Kemet folks show the impedance vs. frequency characteristic for their
various MLC's in this file:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/weben/B3D6942FD742E4A5CA2570A500160908/$file/F3102_CerPerChar.pdf
Given the short connect time, 4ns, of your application it looks like you
will care about the (typical) capacitor's impedance well above series
resonance, which will probably be dominated by ESL. You might want to use
a COG dielectric.
John Larkin
wrote:
>On Tue, 14 Aug 2007 17:58:13 -0700, John Larkin
Well, it depends on your definition of "equivalent." Certainly you can
measure the vector impedance at some frequency and razzle-dazzle some
equations and come up with both an "equivalent" series resistance or,
if you prefer, an "equivalent" shunt resistance. Somebody here just
did that and got 800+ ohms ESR for a ceramic cap.
But that "ESR" is absolutely meaningless for, say, designing a bypass
system or compensating a switching regulator, because it's about
10,000 or so times the true series resistance. And the equivalent
shunt resistance is even-worse useless if you're doing DC design,
because it's maybe a million times off of being predictive of real
leakage current.
So, OK, I was wrong: you can certainly do the calculation, or let some
fancy instrument do it for you, and display it to 5 digits of
precision, and that's fine for people who don't mind being off by 4 to
6 orders of magnitude.
About the only thing a single-frequency ESR measurement does is sort
of predict how the cap will work *at that frequency*
John
John Larkin
<To-Email-Use-Th...@My-Web-Site.com> wrote:
>On Tue, 14 Aug 2007 23:42:47 -0700, The Phantom <pha...@aol.com>
>wrote:
>
>>On Tue, 14 Aug 2007 09:51:38 -0700, Jim Thompson
>><To-Email-Use-Th...@My-Web-Site.com> wrote:
>>
>>>Quick ESR answer needed...
>>>
>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>might I expect?
>>
>> At what frequency? That makes a big difference.
>>
>>>
>>>Client says 0.2 Ohms
>>>
>>>I doubt that number, but don't have anything to base my doubt on.
>>>
>>>What say yee all?
>>>
>>> ...Jim Thompson
>
>If frequency makes a difference then isn't it "ESL" rather than ESR?
>
>Application has capacitor charged to +1.8V, it is then connected (4ns
>full-on connect time) thru a 1.5 Ohm "strap" to -1.8V.
>
>In other words, over 2A peak current.
>
> ...Jim Thompson
Tricky. Assuming a 1 ns risetime, 4 volts available, only 2 nH or so
will get you into trouble. A cap and its leads will get you to about 2
nH, then there's all your wirebonds, not to mention the load itself.
We usually parallel several caps, on a lot of copper, to supply a lot
of fast peak current, like through a gaasfet to drive an SRD or a
laser.
(Gotta get ready for a Board meeting. What a nuisance.)
John
Jim Thompson
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>On Wed, 15 Aug 2007 07:11:54 -0700, Jim Thompson
><To-Email-Use-Th...@My-Web-Site.com> wrote:
>
>>On Tue, 14 Aug 2007 23:42:47 -0700, The Phantom <pha...@aol.com>
>>wrote:
>>
>>>On Tue, 14 Aug 2007 09:51:38 -0700, Jim Thompson
>>><To-Email-Use-Th...@My-Web-Site.com> wrote:
>>>
>>>>Quick ESR answer needed...
>>>>
>>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>>might I expect?
>>>
>>> At what frequency? That makes a big difference.
>>>
>>>>
>>>>Client says 0.2 Ohms
>>>>
>>>>I doubt that number, but don't have anything to base my doubt on.
>>>>
>>>>What say yee all?
>>>>
>>>> ...Jim Thompson
>>
>>If frequency makes a difference then isn't it "ESL" rather than ESR?
>>
>>Application has capacitor charged to +1.8V, it is then connected (4ns
>>full-on connect time) thru a 1.5 Ohm "strap" to -1.8V.
>>
>>In other words, over 2A peak current.
>>
>> ...Jim Thompson
>
>Tricky. Assuming a 1 ns risetime, 4 volts available, only 2 nH or so
>will get you into trouble. A cap and its leads will get you to about 2
>nH, then there's all your wirebonds, not to mention the load itself.
Face-down ball bonded. ~0.5nH connections.
>
>We usually parallel several caps, on a lot of copper, to supply a lot
>of fast peak current, like through a gaasfet to drive an SRD or a
>laser.
>
>(Gotta get ready for a Board meeting. What a nuisance.)
>
>
>John
Me, my wife and my oldest daughter ARE the board... no nuisance ;-)
Joerg
Same here, but no daughter.
Leo
A bit off this topic, I saw a post where you talk about 11801 ("When you
start getting powerup timebase errors, which you will, call
me.") I have an 11801 that has this problem. Would you be able to help me
fix it?
Thank you,
Leo
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
news:k176c31rgpgn9psbq...@4ax.com...
Uwe Bonnes
...
> They may have a lower *ESR*, but for many applications
> (e.g. decoupling) what matters is the total impedance, which is often
> dominated by ESL (inductance). This is usually lower with *smaller*
> devices.
But for switching applications I(ripple)^2* ESR will cause a temperature
rise in the device. More ESR in a smaller device can be catastrophic (ask
Joerg about green molten glass perls...)
--
Uwe Bonnes b...@elektron.ikp.physik.tu-darmstadt.de
Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------
The Phantom
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
Of course it does. I have been explaining the definition used by the
capacitor manufacturers. It's the only (resistance; ESL is another number)
number you will find in their specs, and they get it by simple measurement.
>Certainly you can
>measure the vector impedance at some frequency and razzle-dazzle some
>equations and come up with both an "equivalent" series resistance
That's just what they do, and if a person wants to make sense of their
numbers, he should realize how they got them.
>if you prefer, an "equivalent" shunt resistance. Somebody here just
>did that and got 800+ ohms ESR for a ceramic cap.
I provided that number, and it would accurately tell you the dissipation
in that capacitor if it were handling a 20 Hz current.
>
>But that "ESR" is absolutely meaningless for, say, designing a bypass
>system
It's not meaningless at all. The ESR at a given frequency, for example
120 Hz, tells you just how much power is dissipated in the capacitor for a
given ripple current (assuming the fundamental is 120 Hz. The harmonics
contribute some heat in a typical 120 Hz power supply, but the fundamental
dominates). In a switcher, the ripple current is typically trapezoidal and
the magnitude of the fundamental ripple frequency is still dominant; the
ESR at that frequency gives a good first cut at the dissipation in the
capacitor.
Look at the ripple current ratings of these capacitors:
http://www.cde.com/catalogs/066.pdf
Notice how the ripple current rating is less at lower frequencies.
That's because the ESR increases at low frequencies. The ESR determines
how much heating the ripple current will cause, and it tells it accurately
because the ESR includes all the losses in the capacitor.
>or compensating a switching regulator, because it's about
>10,000 or so times the true series resistance.
This is only true at very low audio frequencies. Up around switching
regulator frequencies, it's probably quite close to the true series
resistance (R1 in your model).
>And the equivalent
>shunt resistance is even-worse useless if you're doing DC design,
>because it's maybe a million times off of being predictive of real
>leakage current.
This is why I asked in another post how we would define DC ESR. It
doesn't make sense at DC, and it's never given at DC. At low audio
frequencies it's defined the same way it's defined at higher frequencies.
It's the real part of the impedance measured at a given frequency.
The model you gave is well known, and it's a good tool for design, but
it's not what the manufacturers give you. You will have to derive it
yourself from a series of measurements, as you said.
>
>So, OK, I was wrong: you can certainly do the calculation, or let some
>fancy instrument do it for you, and display it to 5 digits of
>precision, and that's fine for people who don't mind being off by 4 to
>6 orders of magnitude.
>
>About the only thing a single-frequency ESR measurement does is sort
>of predict how the cap will work *at that frequency*
And this is quite useful in those situations where the ripple current has
a dominant fundamental component, such as in power supply applications. It
tells you what the heating in the cap will be with fair accuracy. In fact,
the error from neglecting the harmonics is probably less that the error
from neglecting the variance in the ESR at a given frequency in a group of
capacitors nominally the same.
Of course, there will be applications where the harmonics are important,
and then the designer will have to derive the more complicated and more
accurate model. But this doesn't detract from the usefulness of the plain
old ESR model in many other cases.
>
>John
>
John Larkin
>Quick ESR answer needed...
>
>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>might I expect?
>
>Client says 0.2 Ohms
>
>I doubt that number, but don't have anything to base my doubt on.
>
>What say yee all?
>
>
While I was waiting for The Board to show up, I cobbled up this:
http://s2.supload.com/free/Setup.JPG/view/
http://s2.supload.com/free/Ramp.JPG/view/
It's a 0.1 uF, 0805 cap soldered across a 50 ohm transmission line.
It's being driven from (we pause for this commercial message...)
http://www.highlandtechnology.com/DSS/P400DS.html
which is setup for 5 volts out, 50 ohms, so it's dumping a 100 mA step
into the cap with about a 1 ns risetime. The scope bandwidth is 20
GHz.
The first glitch is L di/dt, roughly estimated as 1.5 nH.
Extrapolating the slope back to the start gives very roughly 20
milliohms, but it's hard to resolve that small a resistance with this
rig. The glitch at about 10 ns is a cable reflection.
This cap is pretty much a dead short in the, say, 3 ns time frame.
John
John Larkin
>John,
>
>A bit off this topic, I saw a post where you talk about 11801 ("When you
>start getting powerup timebase errors, which you will, call
>me.") I have an 11801 that has this problem. Would you be able to help me
>fix it?
>
>Thank you,
>Leo
If you email me privately, I'll tell you what it probably is and how
to fix it. But promise me you won't spread it around publicly... I
just got a dead 11801A on ebay for $300, and if everybody learns this
trick, they'll all go back up to $3K.
What sort of sampling heads do you have?
John
Winfield Hill
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 14 Aug 2007 09:51:38 -0700, Jim Thompson
>
My hp4192 Impedance Analyzer, outfitted with
an 16034E SMT fixture, used in average mode,
says a Panasonic 0.1uF 25V X7R 0805 cap has
C = 92nF, plus about 36-milliohms of esr.
The Phantom
<jjla...@highNOTlandTHIStechnologyPART.com> wrote:
>On Tue, 14 Aug 2007 09:51:38 -0700, Jim Thompson
><To-Email-Use-Th...@My-Web-Site.com> wrote:
>
>>Quick ESR answer needed...
>>
>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>might I expect?
>>
>>Client says 0.2 Ohms
>>
>>I doubt that number, but don't have anything to base my doubt on.
>>
>>What say yee all?
>>
>>
>
>While I was waiting for The Board to show up, I cobbled up this:
>
>http://s2.supload.com/free/Setup.JPG/view/
>
>http://s2.supload.com/free/Ramp.JPG/view/
>
>
>It's a 0.1 uF, 0805 cap soldered across a 50 ohm transmission line.
>It's being driven from (we pause for this commercial message...)
>
>http://www.highlandtechnology.com/DSS/P400DS.html
>
>which is setup for 5 volts out, 50 ohms, so it's dumping a 100 mA step
>into the cap with about a 1 ns risetime. The scope bandwidth is 20
>GHz.
>
>The first glitch is L di/dt, roughly estimated as 1.5 nH.
>Extrapolating the slope back to the start gives very roughly 20
>milliohms
A detailed description of this technique is to be found at:
http://emcesd.com/tt020100.htm
Joel Kolstad
news:g207c3pspc2r5onn3...@4ax.com...
> http://emcesd.com/tt020100.htm
Thanks for the link, Phantom.
John -- since you're not exactly enamored with Howard Johnson, do you have an
opinion on Doug Smith there? I met him once and he seems to be considerably
more "hands on" than Howard is. (That picture on his web site looks about 10
years old though!)
---Joel
Harry Dellamano
http://www.avxcorp.com/prodinfo_catlist.asp?ParentID=1
Enter in your favorite cap and dielectric, vary the frequency as you watch
the ESR change. Most fun I have had with my cloths on in a long time. See
that ESL does not change with frequency. That is why we do not use large MLC
caps to do AC line filtering, they will let the smoke out.
Regards,
Harry
John Larkin
wrote:
If one eyeball extrapolates my slope down to about the midpoint time
of the inductive glitch, 40 milliohms isn't an unreasonable guess. At
least we aren't disagreeing by 2000:1 or anything like that!
John
Leo
I'll not spread it around. I just got mine (11801A) for about the same
price, but it has an error on power-up. I would like to use for measuring
the input impedance of the microstrip antennas.
I have an old sd-24 sampling head (hopefully working one).
what is your email?
Thanks,
Leo
leomats at gmail.com
"John Larkin" <jjla...@highNOTlandTHIStechnologyPART.com> wrote in message
news:4qt6c3tj6cv4rsqnf...@4ax.com...
Phil Allison
"The Phantom"
> Indeed it does, but this isn't what is meant by manufacturers when they
> talk about ESR. If you measure the impedance of a capacitor at some
> frequency, the real part of the impedance won't be what you have shown as
> R1 if there are any other losses, which there usually are.
>
> I now see why you said "...you can't calculate ESR
> from a single-frequency vector impedance measurement."
>
> This would be true if ESR (as used by the manufacturers of capacitors)
> were R1 in your schematic, but that isn't what they mean by the term.
>
** When cap makers specify the ESR of an electrolytic capacitor - the
impedance value in the broad high frequency ( series self resonance) minimum
area is what is quoted. Ceramic bypass caps are also quoted as being "low
ESR" if their impedance falls to unusually low values at self resonance.
Film caps and others that are likely to be subjected to steep pulses and/or
high AC voltage swings at high frequencies are specified by quoting the
Dissipation Factor or " Tan Delta".
The cap makers are simply supplying useful info to circuit designers engaged
with in particular applications of their products.
Not trying to win a terminology & pedantry contest.
....... Phil
The Phantom
At what frequency, Winfield?
What does the 4192 say for ESR at 20 Hz, 100 Hz, 1000 Hz and 10,000 Hz?
The Phantom
<JKolstad7...@yahoo.com> wrote:
>"The Phantom" <pha...@aol.com> wrote in message
>news:g207c3pspc2r5onn3...@4ax.com...
>> http://emcesd.com/tt020100.htm
>
>Thanks for the link, Phantom.
Another one well worth looking at is:
http://www.avxcorp.com/docs/Catalogs/smpsas&p.pdf
John Larkin
<To-Email-Use-Th...@My-Web-Site.com> wrote:
I wasn't bad: Plant tour, 10 minutes; shareholders' meeting, 5
minutes; board meeting, 35 minutes; lunch at Zuni Cafe, 1 hour.
Chairman John
John Larkin
<JKolstad7...@yahoo.com> wrote:
He seems OK, but not earth-shaking or anything; as you say, very
practical. And thank Goodness he doesn't wear those drecky
turtlenecks.
John
Winfield
At very low frequencies, where the esr is swamped by the
capacitive reactance, the esr measurement resolution and
accuracy is greatly reduced. At very high frequencies,
inductive reactance swamps the esr. While the 4192 and
other vector-based impedance-measuring instruments can
deal with esr values less than 1% of the reactance, etc.,
measurement errors do grow. One assumes that esr changes
little with frequency, and this is completely consistant
with the data, but it's hard to prove with measurements.
Joerg
You mean, no trek down to Gordon Biersch's in the evening?
John Larkin
No, too hoppy for my taste. But my attorney's office (he's a board
member) is just a couple of blocks from GB. He's in the penthouse of
the building at Mission and the Embarcadero, above Boulevard
Restaurant. We're sort of his hobby.
Yeah, here it is:
http://www.noehill.com/sf/landmarks/nat1979000528.asp
John
Joerg
Ever tried their Maerzen? Just don't drive after a couple of those.
> Yeah, here it is:
>
> http://www.noehill.com/sf/landmarks/nat1979000528.asp
>
Nice digs! I guess his hourly rate is quite a bit higher than that of
engineers.
The Phantom
wrote:
Yes, but, what does the 4192 say for ESR at 20 Hz, 100 Hz, 1000 Hz and
10,000 Hz?
Joerg
>
>>Quick ESR answer needed...
>>
>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>might I expect?
>>
>>Client says 0.2 Ohms
>>
>>I doubt that number, but don't have anything to base my doubt on.
>>
>>What say yee all?
>>
>>
>
>
> While I was waiting for The Board to show up, I cobbled up this:
>
> http://s2.supload.com/free/Setup.JPG/view/
>
> http://s2.supload.com/free/Ramp.JPG/view/
>
That server tries some nasty pop-ups. Ricocheted off here, but others
might not be so lucky.
>
> It's a 0.1 uF, 0805 cap soldered across a 50 ohm transmission line.
> It's being driven from (we pause for this commercial message...)
>
> http://www.highlandtechnology.com/DSS/P400DS.html
>
> which is setup for 5 volts out, 50 ohms, so it's dumping a 100 mA step
> into the cap with about a 1 ns risetime. The scope bandwidth is 20
> GHz.
>
What's the ballpark s.e.d. discount price for that one? I am using the
old Philips PM5785B for stuff like this and it's fine for me. But I have
a client who may need to generate test pulses with less jitter than the
Philips can do. How much oomph can you get out of that optional 50V
output? We'd need more than 5V, sometimes a lot more.
> The first glitch is L di/dt, roughly estimated as 1.5 nH.
> Extrapolating the slope back to the start gives very roughly 20
> milliohms, but it's hard to resolve that small a resistance with this
> rig. The glitch at about 10 ns is a cable reflection.
>
> This cap is pretty much a dead short in the, say, 3 ns time frame.
>
--
Regards, Joerg
John Larkin
<notthis...@removethispacbell.net> wrote:
I've only been to Boulevard once, and it was fabulous, but I'm
scheduled there for my next birthday. They do have $3000 bottles of
wine on the list. During the dot.com days, they discovered that the
more they charged for a wine, the more people ordered it. In the year
2000, it was Ground Zero for web-head recruitment dinners.
>
>
>> Yeah, here it is:
>>
>> http://www.noehill.com/sf/landmarks/nat1979000528.asp
>>
>
>Nice digs! I guess his hourly rate is quite a bit higher than that of
>engineers.
$400 or something like that.
John
Jim Thompson
<notthis...@removethispacbell.net> wrote:
>Hello John,
>
>>
>>>Quick ESR answer needed...
>>>
>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>might I expect?
>>>
>>>Client says 0.2 Ohms
>>>
>>>I doubt that number, but don't have anything to base my doubt on.
>>>
>>>What say yee all?
>>>
>>>
>>
>>
>> While I was waiting for The Board to show up, I cobbled up this:
>>
>> http://s2.supload.com/free/Setup.JPG/view/
>>
>> http://s2.supload.com/free/Ramp.JPG/view/
>>
>
>That server tries some nasty pop-ups. Ricocheted off here, but others
>might not be so lucky.
>
>>
[snip]
No such problems here (Firefox v2.0.0.6).
Joerg
I guess they must have really suffered when the dot-com bubble popped.
>
>
>>
>>>Yeah, here it is:
>>>
>>>http://www.noehill.com/sf/landmarks/nat1979000528.asp
>>>
>>
>>Nice digs! I guess his hourly rate is quite a bit higher than that of
>>engineers.
>
>
> $400 or something like that.
>
Ouch. My attorney is around $250 but this is in the country, east of
Sacramento.
Joerg
> On Thu, 16 Aug 2007 18:49:36 GMT, Joerg
> <notthis...@removethispacbell.net> wrote:
>
>
>>Hello John,
>>
>>
>>>>Quick ESR answer needed...
>>>>
>>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>>might I expect?
>>>>
>>>>Client says 0.2 Ohms
>>>>
>>>>I doubt that number, but don't have anything to base my doubt on.
>>>>
>>>>What say yee all?
>>>>
>>>>
>>>
>>>
>>>While I was waiting for The Board to show up, I cobbled up this:
>>>
>>>http://s2.supload.com/free/Setup.JPG/view/
>>>
>>>http://s2.supload.com/free/Ramp.JPG/view/
>>>
>>
>>That server tries some nasty pop-ups. Ricocheted off here, but others
>>might not be so lucky.
>>
>>
> [snip]
>
> No such problems here (Firefox v2.0.0.6).
>
I didn't have any here but you can see the attempts. Only web sites on
the more rough-and-tumble side do that.
John Larkin
<notthis...@removethispacbell.net> wrote:
>Hello John,
>
>>
>>>Quick ESR answer needed...
>>>
>>>Typical 0.22uF ceramic in low voltage application (5V max), what ESR
>>>might I expect?
>>>
>>>Client says 0.2 Ohms
>>>
>>>I doubt that number, but don't have anything to base my doubt on.
>>>
>>>What say yee all?
>>>
>>>
>>
>>
>> While I was waiting for The Board to show up, I cobbled up this:
>>
>> http://s2.supload.com/free/Setup.JPG/view/
>>
>> http://s2.supload.com/free/Ramp.JPG/view/
>>
>
>That server tries some nasty pop-ups. Ricocheted off here, but others
>might not be so lucky.
Oh. I've never seen their popups, just a few static ads. I'm using
Firefox.
>
>>
>> It's a 0.1 uF, 0805 cap soldered across a 50 ohm transmission line.
>> It's being driven from (we pause for this commercial message...)
>>
>> http://www.highlandtechnology.com/DSS/P400DS.html
>>
>> which is setup for 5 volts out, 50 ohms, so it's dumping a 100 mA step
>> into the cap with about a 1 ns risetime. The scope bandwidth is 20
>> GHz.
>>
>
>What's the ballpark s.e.d. discount price for that one? I am using the
>old Philips PM5785B for stuff like this and it's fine for me. But I have
>a client who may need to generate test pulses with less jitter than the
>Philips can do. How much oomph can you get out of that optional 50V
>output? We'd need more than 5V, sometimes a lot more.
List price is $3840, with options for OCXO, Ethernet, and stuff like
that. Jitter for short delays is around 6 ps RMS, increasing to 10's
of ps for long delays. The HV option is $600, and puts 50 volts into
50 ohms with risetime about 1.8 ns. I did this with 2N7002's! I can
email a manual to anybody who's interested.
John
Joerg
I like that classy fluorescent display. Yes, I'd be interested in a manual:
jsc
at ieee dot org
(that one is less typing than my biz email address)
Michael A. Terrell
Good deal! All I got for my birthday (the 5th) was my wallet
disappeared with all my ID, and $150 in cash, which was most of my food
money for this month.
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
Jim Thompson
When I was in my mid 20's I saw Carol Doda in her swing, and fell in
love... at least the lower part of my anatomy did ;-)
Rene Tschaggelar
John,
I'm interested in a manual too.
to tschaggelar (at) dplanet (dot) ch
Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net
Spilchbüel 1, 8342 Wernetshausen, Switzerland
ph. ++41 55 266 19 66 & ++41 44 937 23 67
John Larkin
<To-Email-Use-Th...@My-Web-Site.com> wrote:
I made a business trip to HP in Cupertino, with my bosses, in roughly
the early 1970's, and we went to see Carol at the Condor. I didn't
care too much for her body, preferring ballerina types myself, but she
was actually very talented and her show was a lot of fun. The nasty
parts were projected on a screen behind her, because full live nudity
wasn't allowed in places that sold drinks. That's still the law here,
maybe, I think.
The HP computer group was in a beautiful low glass building in the
middle of a peach orchard. I drove by last year and barely recognized
it... now surrounded by Burger Kings and car dealers and motels and
crap.
John
The Phantom
wrote:
>On Aug 15, 10:35 pm, The Phantom <phan...@aol.com> wrote:
I hope you are using the term "esr" (I prefer to capitalize it) to mean
the same thing the capacitor manufacturers do. They do not use it to mean
the "true series resistance" as John Larkin showed in a more complicated
circuit model that he and I have been discussing. It means the total
losses of the capacitor at a given frequency are lumped together in a
single "equivalent" resistor modeled as if it were in series with the
capacitor. It is the real part of the *impedance* as measured on your 4192
using the series circuit mode.
You say that "One assumes the esr changes little with frequency", and
then you say this is completely consistant with the data. To what data are
you referring, and are you using "esr" to mean what capacitor manufacturers
mean by it? The plots of ESR vs. frequency provided by the manufacturers
all show ESR increasing as frequency decreases into the low audio range.
I would not assume the ESR is (essentially) constant with frequency, but
rather that the dissipation factor is more or less constant with frequency,
say from 100 Hz to 100 kHz. Since the DF is 1/Q, or resistance/reactance
which is R / (1/wC), if it is to remain constant with frequency, then as
1/wC increases with decreasing frequency, so must R. When making
measurements of C on the 4192, display 2 can be set to show Q, D, or R/G.
If you select R/G, then display 2 will show the real part of the
capacitor's impedance, and that is just the ESR. It's all the losses
lumped into one series resistance.
At very low frequencies, ESR is not swamped by the capacitive reactance.
ESR increases at just about the same rate as reactance. Set display 2 on
the 4192 to show Q and see how it varies from 100 Hz to 100 kHz. I did
this with a .1 uF MLC and the Q only varied over a range of 60 to 100 as
the frequency varied 3 orders of magnitude. If Q is to remain more or less
constant, then the ESR must increase just as fast as the capacitive
reactance as frequency decreases. And, in fact, this is just what I see
when I make the measurement.
The data that I've measured shows that ESR varies inversely with
frequency below 100 kHz, typically; it's not constant at all. And this is
just what should be expected. In every case where a manufacturer gives
plots of ESR with frequency, you'll see that it increases as frequency
decreases to low audio.
These conclusions I've given all depend on the definition of ESR as used
by the capacitor manufacturers.
Phil Allison
"The Phantom"
>
> These conclusions I've given all depend on the definition of ESR as used
> by the capacitor manufacturers.
** Complete BOLLOCKS.
Cap makers DATA sheets and published marketing claims all refer to minimum
impedance values at self resonance as being the " ESR ".
...... Phil
Terry Given
> "The Phantom"
>
>
>> These conclusions I've given all depend on the definition of ESR as used
>>by the capacitor manufacturers.
>
>
>
> ** Complete BOLLOCKS.
> Cap makers DATA sheets and published marketing claims all refer to minimum
> impedance values at self resonance as being the " ESR ".
>
>
>
>
> ...... Phil
>
>
heres one that doesnt:
http://us.sanyo.com/industrial/electronic_components/capacitors/os_con/downloads/oscon_chars.pdf
more importantly, it contains graphs of ESR and impedance vs frequency
for a variety of types, and more relevant to this thread, impedance &
ESR measurements versus frequency (1kHz - 40MHz) of 25V 10uF (it appears
X7R) multilayer ceramic caps and the comparable OSCON part, with both 0V
and 20Vdc bias.
Cheers
Terry
Phil Allison
"Terry Given =
a totally ASD Fucked Stinking Kiwi ARSEHOLE and Kiddie Fucker "
>>> These conclusions I've given all depend on the definition of ESR as used
>>>by the capacitor manufacturers.
>>
>>
>> ** Complete BOLLOCKS.
>>
>> Cap makers DATA sheets and published marketing claims all refer to
>> minimum impedance values at self resonance as being the " ESR ".
>>
>>
>
> heres one that doesnt:
** No interested in following the context are you - cunthead ???
Not now, nor at any time in your whole, miserable fucking life.
Cos YOU have absolutely NO FUCKING IDEA what that word means.
Cos YOU are a genetic, autistic metal defective.
So, YOU are sub human GARBAGE
A failed, brain dead New Zealand, Pin Ball Machine Mechanic !!
YOU are one vile piece of shit - Given.
A narcissistic, TROLLING anonymous criminal charlatan.
A total waste of space.
........ Phil
John Larkin
wrote:
>On Thu, 16 Aug 2007 07:11:37 -0700, Winfield <winfie...@yahoo.com>
I don't think capacitor manufacturers are consistant in what they mean
by ESR, or how they measure it. I suspect that many of them don't
really understand what's going on, and buy some instrument that
reports some number, and believe it.
In low impedance circuits, which a lot of us do a lot of the time, the
LSR (Larkin Series Resistance) is what matters, and no 0.1 uF ceramic
cap is going to have 800 ohms of LSR.
John
Fred Bloggs
Right, well you're more concerned with a circuit theoretic model insofar
as determining transient time constants. The component manufacturers
are more concerned with deviation from ideality in terms of
"dissipation factor" or deviation from behavior of an ideal energy
storage element. These ideas are trivial.
Straw Man
"Phil Allison" =
" a totally ASD Fucked Stinking ARSEHOLE and Dog Fucker "
Fred Bartoli
Congrats...
You've just wont your flush down to the toilets.
Plonk.
--
Thanks,
Fred.
Jim Thompson
wrote:
Oh, Fred, You're just so brilliant! Swoon some more ;-)
The Phantom
You've left the phrase "capacitor manufacturers" unqualified. Do you mean
"all", "most", "some", or "a few" manufacturers? Can you offer any examples
(web pages or pdf files) to support your assertion?
> I suspect that many of them don't
>really understand what's going on, and buy some instrument that
>reports some number, and believe it.
I think they understand full well. They buy an instrument that can measure
the vector impedance of a capacitor, and they report the real part of that
impedance at a given frequency, or they provide a plot of the real part vs.
frequency, calling it ESR. If their instrument says that the real part of the
impedance of one of their capacitors at a given frequency is some value, why
shouldn't they believe it? The model (the ESR model) they are using is just an
ideal capacitor in series with a single resistor, and the value of that resistor
in the model is just the real part of the impedance, as measured. This value
varies with frequency as I explain below.
>
>In low impedance circuits, which a lot of us do a lot of the time, the
>LSR (Larkin Series Resistance) is what matters, and no 0.1 uF ceramic
>cap is going to have 800 ohms of LSR.
The cap I measured with an 800 ohm ESR was .27 uF, not .1 uF. I dug out a .1
uF cap and its measured ESR at 20 Hz is 2200 ohms.
Assuming the LSR of a capacitor is what you have shown as R1 in your more
complicated model (reproduced below), I would agree that no .1 uF ceramic cap
will have a model value for R1 of 800 ohms (or even 2200 ohms). I've never made
any such claim. But if you derive the parameters for a .1 uF cap using your
model, and then do the algebra to reduce it to a two terminal impedance at 20
Hz, with a real and an imaginary part, the real part will be about 2200 ohms (if
your cap has the same dielectric as mine). But whatever dielectric, the real
part of the 20 Hz impedance (the ESR) will be much larger than R1.
Let me re-iterate. These high ESR's (which are not the same as the LSR) only
occur at very low frequencies. I understand that your business involves very
fast pulses and low impedances, but if you were to design a 20 Hz notch filter
with the .1 uF capacitor I just measured, and you wanted to analyze the
performance, you would have to use a 2200 ohm resistor in series with an ideal
.1 uF capacitor (at 20 Hz, for example, and if the capacitor model, the ESR
model, consisted of an ideal capacitor in series with only a single resistor)
to account for the Q lowering losses in the capacitor. The R1 value (the LSR,
probably 10 to 40 millohms) in *your* model would not be the correct value to
account for the losses at 20 Hz, if the model used was just an ideal capacitor
in series with a single resistor, which is the ESR model used by the
manufacturers.
There is absolutely nothing wrong with the more accurate model you have given
in another post:
---------+
|
L1
|
|
R1
|
+--------+----- etc, if you're
| | compulsive
C1 C2
| |
| |
| R2
| |
| |
---------+--------+------
But its R1 value is not the same at low frequencies as the ESR given by the
capacitor manufacturers, although it is essentially the same at high
frequencies. However, you can calculate the ESR at any frequency by reducing
all those parallel and series branches to a single two terminal impedance. The
ESR is the real part of that result.
Suppose you derive values for L1, R1, C1, C2, R2, etc., for the .1 uF
capacitor and then let the frequency be 20 Hz. Then calculate all those
parallel and series branches, finally arriving at a single impedance between the
external terminals; a simple textbook exercise. The impedance will have a real
and an imaginary part, and that impedance would also be the impedance of an
ideal capacitance of some value in series with a resistance of some value, the
"equivalent" series resistance. At 20 Hz, this "equivalent" series resistance
will be much larger than R1.
If you use your model with its 5 parameters directly in the analysis of the 20
Hz notch filter at 20 Hz, you will get the same result as when first reducing to
a single ideal capacitor in series with an "equivalent" series resistor, if the
reduction is done at 20 Hz. (You better get the same result, or there's a
mistake in the algebra.) If you want the performance at another frequency, then
you could use your model directly, or do the reduction to a capacitor in series
with a single resistor at the new frequency, in which case the "equivalent"
series resistor will have a different value, but it will give the correct result
at this new frequency. So the "equivalent" series resistor will have a
different value at different frequencies.
It's the very presence of C2 and R2 in your model that gives rise to an
"equivalent" series resistance that varies with frequency. If C2 and R2 were
absent, then the ESR would equal R1 (and LSR) at all frequencies.
And at high frequencies (fast pulses) where you like to operate, if you do
this same reduction, the "equivalent" series resistance will be very close to
the value of R1.
This means that the ESR at high frequencies as reported by the capacitor
manufacturers is a useful number for you; it's essentially the same as the LSR
for that capacitor.
Your model has the advantage that the parameters don't vary with frequency,
and could be used in a spice analysis directly. The ESR model has a resistance
that varies with frequency, but it's easier for the manufacturers to provide
this information since all they have to do is measure the real part of the
impedance, and in a lot of cases all the user needs is an approximation for the
losses at a single frequency.
>
>John
>
Winfield Hill
> The HV option is $600, and puts 50 volts into
> 50 ohms with risetime about 1.8 ns. I did this
> with 2N7002's!
Yep. How many 2n7002s are you using?
> I can email a manual to anybody who's interested.
I'd like one. Is there an educational discount?
John Larkin
wrote:
>John Larkin wrote:
>> The HV option is $600, and puts 50 volts into
>> 50 ohms with risetime about 1.8 ns. I did this
>> with 2N7002's!
>
> Yep. How many 2n7002s are you using?
Two. And a transmission-line transformer, for output isolation.
Here's a 50-volt pulse into 50 ohms:
http://s2.supload.com/free/MVC-361X.JPG/view/
If you really believed the 2n7002 datasheets, you wouldn't even try
it.
>
>> I can email a manual to anybody who's interested.
>
> I'd like one. Is there an educational discount?
OK, will do.
Sorry, no.
John
Harry Dellamano
"Winfield Hill" <hi...@rowland.org> wrote in message
news:1187547591.4...@19g2000hsx.googlegroups.com...
Cheers,
Harry
John Larkin
Ah. Humor. No, they don't.
John
Winfield
> Winfield Hill wrote:
>> John Larkin wrote:
>>> The HV option is $600, and puts 50 volts into
>>> 50 ohms with risetime about 1.8 ns. I did this
>>> with 2N7002's!
>
>> Yep. How many 2n7002s are you using?
>
> Two. And a transmission-line transformer, for output
> isolation. Here's a 50-volt pulse into 50 ohms:
> http://s2.supload.com/free/MVC-361X.JPG/view/
Nice looking waveform.
> If you really believed the 2n7002 datasheets, you
> wouldn't even try it.
You used two in parallel to pull up, and two more
in parallel to pull down? Or one each up and down?
Followed by a 50-ohm source-termination resistor?
That's 25 volts at the end of a terminated 50-ohm
line -- 500mA into the output, or 1A into a short?
What's the power rating of your 50-ohm resistor?
John Larkin
wrote:
Two fets, and both pull down, and drive a 1:1 transmission-line
transformer into the load; that makes the gate drive simple. Our
output is low impedance, so delivers 50 volts, 1 amp, into the
customer's 50 ohm load. The scope pic is really 50 volts into a 50-ohm
load, namely a 40 dB attenuator at the scope sampling head.
Our front-panel outputs are true 50-ohm sources, programmable from -4
to +12 low/high open-circuit levels, but that's a fairly awful (ie,
component-rich) GaAs thing.
I sure wish somebody would make a nice "pin driver" chip: programmable
Vl:Vh, lots of swing, clean and fast, reasonably affordable. GBL had
one, back when they were still alive, but it was like $120 a pop or
something silly. I'm thinking that something could be done from a
diode steering network and a couple of really fast TI opamps... gotta
try that some day.
John
Winfield Hill
> Winfield wrote:
>> John Larkin wrote:
>>> Winfield Hill wrote:
>>>> John Larkin wrote:
>
>>>>> The HV option is $600, and puts 50 volts into
>>>>> 50 ohms with risetime about 1.8 ns. I did this
>>>>> with 2N7002's!
>
>>>> Yep. How many 2n7002s are you using?
>
>>> Two. And a transmission-line transformer, for output
>>> isolation. Here's a 50-volt pulse into 50 ohms:
>>> http://s2.supload.com/free/MVC-361X.JPG/view/
>
>
> simple. Our output is low impedance, so delivers 50 volts,
> 1 amp, into the customer's 50 ohm load. The scope pic is
> really 50 volts into a 50-ohm load, namely a 40 dB
> attenuator at the scope sampling head.
So, if there's a long 50-ohm coax, with an open
output, you get a 100-volt pulse lasting twice
the delay through the transmission line?
What's the maximum pulse length with this setup?
John Larkin
wrote:
Yup, and the aftermath would be really ugly. But, as far as I know, it
won't destroy the fets.
>
> What's the maximum pulse length with this setup?
There's graphs in the manual, sec 5.11. The cores saturate around 200
ns or so at 50 volts. If you fire all 5 channels at 50 volts, that's
250 watts out, and we can't keep that up for long!
John