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J.A. Gill tantalum
for some interesting papers.
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
jlarkin@highlandsniptechnology.com wrote:
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
Thanks. I could not remember the name polymer.
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage.
Am 30.08.20 um 07:16 schrieb jlarkin@highlandsniptechnology.com:
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage.
That was written already in the NEC data sheets as of 30 years ago.
Or limit inrush current.
For a space project, to my surprise I had only to derate 1:2.
But then, the only allowed tantalums had already 6 times
the volume of equivalent commercial ones.
Or use polymer aluminums unless you need the ESR.
.... and if you don\'t care about the leakage current.
This here does not work:
Given is JFET amplifier with very low noise specs.
CS at AF. Source current is enforced by CCS, with
10mF from source to GND. The CCS is clean.
FETs were IF3602. They have an updated data sheet btw.
Looks like IF have admitted to the complaints of
Fred Bertoli as of s.e.d. from 15 years ago, and my
observations. No longer interesting.
With polymer electrolytics, the lower 1/f corner was a
few 100 Hz. And with 1/f I really do mean 1/f**4,
40 dB/decade.
With Nippon Chem ALU the corner was much better,
maybe 20 Hz, but still steep.
With AVX wet slug tantalum, the effect was gone at a
cost of 100⬠per 4700uF/25V. Vishay would have asked
twice that. (both @ DK)
Probably with the ws tantalum the effect was also not
really gone, only low enough in frequency that it did
not matter any more. The ws tant still has 200 mOhm
series resistance as seen on the bridge, fits data sheet.
I was puzzled by the steepness >> 1/f. It probably
takes a process that collects energy over a long time
and then breaks suddenly. The longer it takes, the
more energy will be released, like an earth quake.
cheers, Gerhard
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
An electrolytic cap has a certain amount in common with a dead battery,
whose cell potential is temperatured-dependent, so a slow temperature
drift will quite plausibly cause 1/f**4 noise.
Am 30.08.20 um 15:57 schrieb Phil Hobbs:
An electrolytic cap has a certain amount in common with a dead
battery, whose cell potential is temperature-dependent, so a slow
temperature drift will quite plausibly cause 1/f**4 noise.
Sorry, it is only 30 dB/decade.
https://www.flickr.com/photos/137684711@N07/50286357721/in/dateposted-public/lightbox/
       Â
The other traces mostly follow the Agilent 89441A.
cheers, Gerhard
Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
Thanks. I could not remember the name polymer.
Here\'s a brief review of polymer caps:
Learning About Polymer Capacitors - The Learning Circuit
https://www.youtube.com/watch?v=sLF1QMVMJi8
Replacing MLCCs with Polymer Capacitors - The Learning Circuit
https://www.youtube.com/watch?v=l-GqRMdc7ag
Panasonic manufactures a wide variety of polymer related caps:
Panasonic Polymer Capacitors: an alternative to MLCCs & Tantalum capacitors
https://www.youtube.com/watch?v=j7qHC2gQYBk
Am 30.08.20 um 07:16 schrieb jlarkin@highlandsniptechnology.com:
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage.
That was written already in the NEC data sheets as of 30 years ago.
Or limit inrush current.
For a space project, to my surprise I had only to derate 1:2.
But then, the only allowed tantalums had already 6 times
the volume of equivalent commercial ones.
Or use polymer aluminums unless you need the ESR.
... and if you don\'t care about the leakage current.
This here does not work:
Given is JFET amplifier with very low noise specs.
CS at AF. Source current is enforced by CCS, with
10mF from source to GND. The CCS is clean.
FETs were IF3602. They have an updated data sheet btw.
Looks like IF have admitted to the complaints of
Fred Bertoli as of s.e.d. from 15 years ago, and my
observations. No longer interesting.
With polymer electrolytics, the lower 1/f corner was a
few 100 Hz. And with 1/f I really do mean 1/f**4,
40 dB/decade.
With Nippon Chem ALU the corner was much better,
maybe 20 Hz, but still steep.
With AVX wet slug tantalum, the effect was gone at a
cost of 100 per 4700uF/25V. Vishay would have asked
twice that. (both @ DK)
Probably with the ws tantalum the effect was also not
really gone, only low enough in frequency that it did
not matter any more. The ws tant still has 200 mOhm
series resistance as seen on the bridge, fits data sheet.
I was puzzled by the steepness >> 1/f. It probably
takes a process that collects energy over a long time
and then breaks suddenly. The longer it takes, the
more energy will be released, like an earth quake.
cheers, Gerhard
On 2020-08-30 01:16, jlarkin@highlandsniptechnology.com wrote:
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
I hardly use tantalums for anything nowadays.
One nice feature of alpos is that they come in a wide range of ESR for
the same capacitance and voltage rating.
To make bringup easier I often put zero-ohm jumpers in series with
regulator outputs (on the far side of the feedback network). That has
the useful side effect of adding a few tens of milliohms, which is often
just right for stability. If not, a nice pulse-rated current sense
resistor fixes it right up.
A question for the assembled multitude: Since there\'s nothing to dry out
in an alpo, does it really make sense to rate them for time@temperature
as if they were wet electros?
I mean, what\'s the mechanism for a 1 khr @ 105C rating being different
from 10 khr @ 105C?
Cheers
Phil Hobbs
Am 30.08.20 um 07:16 schrieb jlarkin@highlandsniptechnology.com:
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage.
That was written already in the NEC data sheets as of 30 years ago.
Or limit inrush current.
For a space project, to my surprise I had only to derate 1:2.
But then, the only allowed tantalums had already 6 times the volume of
equivalent commercial ones.
On Sun, 30 Aug 2020 10:22:53 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-30 01:16, jlarkin@highlandsniptechnology.com wrote:
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
I hardly use tantalums for anything nowadays.
One nice feature of alpos is that they come in a wide range of ESR for
the same capacitance and voltage rating.
To make bringup easier I often put zero-ohm jumpers in series with
regulator outputs (on the far side of the feedback network). That has
the useful side effect of adding a few tens of milliohms, which is often
just right for stability. If not, a nice pulse-rated current sense
resistor fixes it right up.
A question for the assembled multitude: Since there\'s nothing to dry out
in an alpo, does it really make sense to rate them for time@temperature
as if they were wet electros?
I mean, what\'s the mechanism for a 1 khr @ 105C rating being different
from 10 khr @ 105C?
I\'ve heard that moisture intrusion hurts polymer caps, as moisture
loss hurts wet aluminums. Both need good seals.
I\'ve posted my trick for getting LM317/1117 type regs to be happy with
ceramic loads.
On 2020-08-30 11:54, jlarkin@highlandsniptechnology.com wrote:
On Sun, 30 Aug 2020 10:22:53 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-30 01:16, jlarkin@highlandsniptechnology.com wrote:
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
I hardly use tantalums for anything nowadays.
One nice feature of alpos is that they come in a wide range of ESR for
the same capacitance and voltage rating.
To make bringup easier I often put zero-ohm jumpers in series with
regulator outputs (on the far side of the feedback network). That has
the useful side effect of adding a few tens of milliohms, which is often
just right for stability. If not, a nice pulse-rated current sense
resistor fixes it right up.
A question for the assembled multitude: Since there\'s nothing to dry out
in an alpo, does it really make sense to rate them for time@temperature
as if they were wet electros?
I mean, what\'s the mechanism for a 1 khr @ 105C rating being different
from 10 khr @ 105C?
I\'ve heard that moisture intrusion hurts polymer caps, as moisture
loss hurts wet aluminums. Both need good seals.
Hmm, maybe so. The chemical potential driving the diffusion is very
different in the two cases though--AFAICT there\'d be no particular
reason for water to diffuse preferentially into the cap unless it were
underwater.
I\'ve posted my trick for getting LM317/1117 type regs to be happy with
ceramic loads.
Yeah, it\'s strange-looking--one would initially expect that to make it
worse. Looking at the FB pin as the input of an op amp, it does provide
some phase lead as well as gain peaking. With 10 nF to ground and 250
ohms from the output, it\'ll provide a phase lead from some lowish
frequency out to about 70 kHz. A big alpo could easily drag the loop
bandwidth of an LM317 down into that range.
Cheers
Phil Hobbs
On Sun, 30 Aug 2020 15:06:34 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-30 11:54, jlarkin@highlandsniptechnology.com wrote:
On Sun, 30 Aug 2020 10:22:53 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
On 2020-08-30 01:16, jlarkin@highlandsniptechnology.com wrote:
On Sun, 30 Aug 2020 04:33:34 GMT, Steve Wilson <spam@me.com> wrote:
jlarkin@highlandsniptechnology.com wrote:
J.A. Gill tantalum
for some interesting papers.
We all know the limitations of tantalum. What are the alternatives?
Derate 3:1 on voltage. Or use polymer aluminums unless you need the
ESR.
Or ceramics.
A few old regulators need the esr to be stable.
I hardly use tantalums for anything nowadays.
One nice feature of alpos is that they come in a wide range of ESR for
the same capacitance and voltage rating.
To make bringup easier I often put zero-ohm jumpers in series with
regulator outputs (on the far side of the feedback network). That has
the useful side effect of adding a few tens of milliohms, which is often
just right for stability. If not, a nice pulse-rated current sense
resistor fixes it right up.
A question for the assembled multitude: Since there\'s nothing to dry out
in an alpo, does it really make sense to rate them for time@temperature
as if they were wet electros?
I mean, what\'s the mechanism for a 1 khr @ 105C rating being different
from 10 khr @ 105C?
I\'ve heard that moisture intrusion hurts polymer caps, as moisture
loss hurts wet aluminums. Both need good seals.
Hmm, maybe so. The chemical potential driving the diffusion is very
different in the two cases though--AFAICT there\'d be no particular
reason for water to diffuse preferentially into the cap unless it were
underwater.
I\'ve posted my trick for getting LM317/1117 type regs to be happy with
ceramic loads.
Yeah, it\'s strange-looking--one would initially expect that to make it
worse. Looking at the FB pin as the input of an op amp, it does provide
some phase lead as well as gain peaking. With 10 nF to ground and 250
ohms from the output, it\'ll provide a phase lead from some lowish
frequency out to about 70 kHz. A big alpo could easily drag the loop
bandwidth of an LM317 down into that range.
It doesn\'t make sense, but it works fine. The cap has to be the right
size. I discovered it experimentally, but it works with a couple of
different 317 Spice models, too.
Just a big cap from ADJ to ground doesn\'t help.
An alpo or a tantalum stabilizes a 317, as long as you don\'t put too
many ceramic bypasses on the board too.