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'[EE] 1.0 uF Decoupling Cap - A Must?'
2009\04\15@200343 by solarwind

picon face
I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
are the newer ones that require no external caps for the charge pumps.
However, the data sheet says to use a 1 uF capacitor from VCC to VDD.
Why 1 uF? I have none of these. Would a 0.1 uF cermic cap work just as
well or is there some weird requirement that it has to be 1 uf?

-- [ solarwind ] --

2009\04\15@204350 by davidcou

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My advise is to use a 0.1uF in parallel with a 10uF (or 22uF) if you have them.

The goal is to provide a local current path as close to the Maxim IC for the internal switching system.

The 1uF is a minimum recommendation but I always recommend a 0.1uF additionally as close to the IC.




{Original Message removed}

2009\04\15@205200 by solarwind

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On Wed, Apr 15, 2009 at 8:43 PM,  <spam_OUTdavidcouTakeThisOuTspamaol.com> wrote:
> My advise is to use a 0.1uF in parallel with a 10uF (or 22uF) if you have them.
>
> The goal is to provide a local current path as close to the Maxim IC for the internal switching system.
>
> The 1uF is a minimum recommendation but I always recommend a 0.1uF additionally as close to the IC.

Thanks. I'll do the 10 uF + 0.1 uF.

2009\04\16@052432 by Tamas Rudnai

face picon face
As far as I remember couple of guys here bet on the 1.0uF ceramic ones (or
other low ESR) - Olin was talking about that a while ago I think. Couple of
days ago someone else here (sorry, could not recall his name) said 1.0uF is
not good for low drop regulators. I guess all depends on your application,
power source etc.

Tamas


On Thu, Apr 16, 2009 at 1:51 AM, solarwind <.....x.solarwind.xKILLspamspam@spam@gmail.com> wrote:

{Quote hidden}

> -

2009\04\16@084926 by olin piclist

face picon face
solarwind wrote:
> I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
> are the newer ones that require no external caps for the charge pumps.
> However, the data sheet says to use a 1 uF capacitor from VCC to VDD.
> Why 1 uF?

Unless the datasheet decides to explain the reasoning behind it or you can
talk to a Maxxim engineer envolved in the design, don't expect to ever know.
What you need to know is that's the spec.

My guess is that the internal charge pump draws current in bursts and can't
guarantee the output voltage and current specs if the supply is allowed to
droop.  They are probably assuming a barely good enough impedence of the
power supply especially once it reaches the chip, and they found 100nF
insufficient to cover their butts, so specified 1uF.

> I have none of these. Would a 0.1 uF cermic cap work just as
> well or is there some weird requirement that it has to be 1 uf?

There is a requirement since the datasheet clearly says so.  100nF would
probably work most of the time if you have a good power supply, but I would
use the 1uF.  The days of 100nF bypass caps are long gone for "normal" ICs
anyway.  Yes I know lots of people still tell you to use 100nF caps, but
that's a sign they haven't kept up and should be a warning they probably
don't know other things they are talking about either.  Today's 0805
multilayer ceramic 1uF caps have lower inductance and higher resonant
frequency than the 100nF caps of a few years ago, even though those were
considered adequate at the time.  I can only recall using less than 1uF
decoupling cap in one circuit in the last 8 or so years where 1uF 0805
ceramic caps have been cheaply and widely avaialable.  That was a RF circuit
where the higher resonant frequency of a 100pF cap of a specific model was
important.  Each power lead to the chip had its own 10ohms in series follwed
by this specific 100pF to ground.  The common supply point before all this
still had the 1uF to ground though.

So the point is if you don't have 1uF 0805 ceramic caps you should get some.

If you have a larger than 1uF ceramic cap you can use that instead.
Anything ceramic of 1uF of higher should be good enough as the power supply
cap for a MAX232 chip.  Do not substitute electrolytic though.  These don't
have the frequency response to work in this situation.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@085120 by olin piclist

face picon face
davidcou@aol.com wrote:
> The 1uF is a minimum recommendation but I always recommend a 0.1uF
> additionally as close to the IC.

Always!!?  That's just silly.  Do you specifiy the species of dead fish to
wave over it too?


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@090019 by olin piclist

face picon face
Tamas Rudnai wrote:
> Couple of days ago someone else here (sorry, could not recall his name)
> said 1.0uF is not good for low drop regulators.

Huh?  There seems to be a lot of dead fish waving here today.

All LDOs that I recall reading the datasheets of require some output
capacitance for stability.  Most also specify some minimum input capacitance
because they need low input impedence.  The gotcha is some LDOs,
particularly but not limited to the cheap asian ones, require a minimum ESR
of the output cap for stability.  Unless you are doing a high volume design
where the extra $.10 matters, you should stick to a LDO that is stable down
to 0 ESR output cap.  You can get yourself into trouble with the ones that
require a minimum ESR if you don't know exactly what you're doing.  Anyone
that has to ask about decoupling here or uses rules of thumb and lore as a
substitute for real understanding need not apply.

This is one thing I like about the Microchip MCP1700 and MCP1702 LDOs.  They
are guaranteed stable with 0 ESR output caps.  This means you can (and
should) put a SMD ceramic cap right accross the output pins as close to the
LDO as possible.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@090146 by davidcou

picon face
I should have said "I usually additionally recommend a .1uF" --- But, I always listen to what Olin has to say.....







{Original Message removed}

2009\04\16@090831 by alan smith

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For one thing...if an app note says..use a low ESR 1uF cap across these pins, its a pretty safe bet that you need to, since it is an app note from the manufacturer.  Read and understand the datasheet Solar..it will really get you pretty far.  Also look for other app notes dealing with the chip..any chip you use.  Its the same as the (pick your favorite car maker) you should add oil to the crankcase.  Sure, you might get pretty far without it, but at some point it will come back to you, for not following the recomendations.


--- On Thu, 4/16/09, Olin Lathrop <.....olin_piclistKILLspamspam.....embedinc.com> wrote:

{Quote hidden}

> --

2009\04\16@092013 by Mike Harrison

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face
On Thu, 16 Apr 2009 09:02:28 -0400, you wrote:

{Quote hidden}

Whearas the MCP1701 does specify a min ESR of 0R1 - min ESR requirements are not all that common but
something you do need to watch for, and not something that you'd necessarily expect if you'd not
previously read a lot of regulator datasheets..!

2009\04\16@100459 by olin piclist

face picon face
Mike Harrison wrote:
>> This is one thing I like about the Microchip MCP1700 and MCP1702 LDOs.
>> They are guaranteed stable with 0 ESR output caps.
>
> Whearas the MCP1701 does specify a min ESR

Which is exactly why I didn't mention it.  I don't like the MCP1701 much.
It looks like it was a intermediate product on the way to the MCP1702.

> min ESR requirements are not all that common

Really?  Over half of the LDOs I've looked at don't allow 0 ESR output caps.
I'd say this issue is common.  Last time I looked into it was maybe a couple
of years ago, and at that time not a single one of the cheap asian LDOs were
specified to work with 0 ESR output cap.  Some ignored the issue which is
even worse.  Can you show me one that specifically says it works with a 0
ESR output cap?


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@105933 by Michael Hagen

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face
The 1700 specifies 0-2 ohms ESR (Spec,Sec 5.2).

I bought some a few months ago, they were not available, but Microchip
Direct had them.
Shipped from the factory, I was presently suppressed and with the price?



{Original Message removed}

2009\04\16@112130 by olin piclist

face picon face
Michael Hagen wrote:
> I bought some a few months ago, they were not available,

Then you couldn't have bought any.

> but Microchip Direct had them.

So they were available.

> Shipped from the factory, I was presently suppressed

I guess I'd be "suppressed" too if I were shipped from a factory.  Did you
at least get your own crate and pallet, or did you have to share it?  Hmm.
How many people can you fit in a standard shipping crate nowadays, and how
much cheaper is it?

> and with the price?

I have no idea what you are trying to ask here.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@114228 by Michael Hagen

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face
Funny.
That was supposed to be Surprised!  Good old spelling checker got me.

I was trying to state that they were out of stock at my usual sources
(Mouser and Digikey) so
I directly ordered them.  The price was competitive and delivery from the
factory was less than a week.
So, I had a good experience with Microchip direct.

Anyway I was answering the question about ESR,  the data sheet definitely
states 0-2 ohms on this device,
making me able to take a resistor in series with the output cap off my
board.  Nice part!

It seemed like some asking if any LDO's could use 0 or near 0 ESR caps?

I checked today, Mouser had the 5V ones.

Mike
{Original Message removed}

2009\04\16@123825 by M. Adam Davis

face picon face
On Thu, Apr 16, 2009 at 8:53 AM, Olin Lathrop <KILLspamolin_piclistKILLspamspamembedinc.com> wrote:
> RemoveMEdavidcouTakeThisOuTspamaol.com wrote:
>> The 1uF is a minimum recommendation but I always recommend a 0.1uF
>> additionally as close to the IC.
>
> Always!!?  That's just silly.  Do you specifiy the species of dead fish to
> wave over it too?

I knew someone who, as a regular part of their engineering, specified
"Sprinkle caps."

He'd add a few dozen capacitors across the power supply on one sheet
of the schematic, and told the layout guy to just sprinkle them all
over the board randomly (which is to say, the layout guy inevitibly
put them where it was convenient for him).  The boards were 4+ layer,
with power and ground layers, chips had their own (correctly rated)
bypass capacitors, etc.

Turns out he failed an EMI test once, and ever since simply placed a
bunch of caps all over to avoid later failures, "Cheaper than
retesting!"  ... except for the most popular products ...

Engineering by the seat of your pants.

Also, regarding the dead fish, I usually specify fresh salmon, and
have a grill standing by for the conclusion of the test.

-Adam

2009\04\16@142506 by Vitaliy

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Olin Lathrop wrote:
> If you have a larger than 1uF ceramic cap you can use that instead.
> Anything ceramic of 1uF of higher should be good enough as the power
> supply
> cap for a MAX232 chip.  Do not substitute electrolytic though.  These
> don't
> have the frequency response to work in this situation.

Olin, you haven't read the datasheet yourself, have you? It says nothing
about not using electrolytics.


alan smith wrote:
> For one thing...if an app note says..use a low ESR 1uF cap across these
> pins, its a pretty safe bet that you need to,

It says nothing about "low ESR", either. Any cap will do.

You guys seem to forget that these are level shifter circuits, not
microcontrollers. The cap is there simply to keep the voltage on RS232 from
going too far below 10V, for the duration of the bit.

Vitaliy

2009\04\16@142728 by Vitaliy

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face
solarwind wrote:
>I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
> are the newer ones that require no external caps for the charge pumps.

Yeah, it's great that you don't need external caps for charge pumps, but you
end up overpaying $8 per IC compared to, say, MAX221. Is it really worth it?

Vitaliy

2009\04\16@153729 by solarwind

picon face
Haha, thanks everyone for the detailed info! For now, I just stuck in
a 10 uF + 0.1 uF until I buy some 1 uF. The thing also works perfectly
without any capacitor at all, but that's probably because I'm powering
it from USB.

I never intended to question the datasheet. I just wanted to know what
was the reasoning behind the 1 uF choice since everyone keeps telling
me to use 0.1 uF. I also wanted to know if there was an alternative
since I did not have any 1 uF caps available.

Also, I wonder why my very simple topics always get so long, deep and
sometimes violent :P

Anyway, thanks again to all! My MAX233A works beautifully! I love
being able to program and test while viewing output without touching
my device. Development goes far more rapidly!

2009\04\16@164555 by Herbert Graf

picon face
On Wed, 2009-04-15 at 20:03 -0400, solarwind wrote:
> I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
> are the newer ones that require no external caps for the charge pumps.
> However, the data sheet says to use a 1 uF capacitor from VCC to VDD.
> Why 1 uF? I have none of these. Would a 0.1 uF cermic cap work just as
> well or is there some weird requirement that it has to be 1 uf?

Generally, if the datasheet says use something, just use it. There is
often a reason for these things (the reason of which may be very
surprising) and it's best to just follow the directions.

That said, and this is pure speculation: those chips have charge pumps.
Charge pumps can sink relatively large amounts for currents for very
short periods of time. Specing such a large bypass is probably also to
ensure the droop on Vcc isn't beyond and acceptable level.

So, with that said, it would probably be OK to use two caps, a 0.1uF for
"normal" bypass reasons (i.e. noise on Vcc) and say a 10uF to minimize
the droop. Note that this recommendation is based on PURE speculation as
to the reason for the spec.

TTYL

2009\04\16@171048 by solarwind

picon face
On Thu, Apr 16, 2009 at 2:26 PM, Vitaliy <spamBeGonespamspamBeGonespammaksimov.org> wrote:
> solarwind wrote:
>>I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
>> are the newer ones that require no external caps for the charge pumps.
>
> Yeah, it's great that you don't need external caps for charge pumps, but you
> end up overpaying $8 per IC compared to, say, MAX221. Is it really worth it?
>
> Vitaliy

It is when you get them for free :)

2009\04\16@180226 by Vitaliy

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solarwind wrote:
>>>I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
>>> are the newer ones that require no external caps for the charge pumps.
>>
>> Yeah, it's great that you don't need external caps for charge pumps, but
>> you
>> end up overpaying $8 per IC compared to, say, MAX221. Is it really worth
>> it?
>>
>> Vitaliy
>
> It is when you get them for free :)

I thought you never got your Maxim shipment? Something about customs duties?

Vitaliy

2009\04\16@183001 by olin piclist

face picon face
Vitaliy wrote:
> Olin, you haven't read the datasheet yourself, have you? It says
> nothing about not using electrolytics.

We're talking about power supply "bypass" or "decoupling" caps.  Basic
electronics should be enough to assume that electrolytics are not suited for
this application unless the datasheet specifically says so, and I expect it
doesn't.  There is really no place left today for a 1uF electrolytic
capacitor.

> It says nothing about "low ESR", either. Any cap will do.

It may not say anything about ESR, but this gets to the level of obvious
unless the datasheet specifically says otherwise.  At some point they have
to rely on the person reading the datasheet to know at least a little about
electronics.  Keep in mind that even though a electrolytic would not be
violating the datasheet if taken literally, neither would a ceramic, and
there are plenty of good reasons to use a ceramic instead of a electrolytic
in this case.

> You guys seem to forget that these are level shifter circuits, not
> microcontrollers. The cap is there simply to keep the voltage on
> RS232 from going too far below 10V, for the duration of the bit.

It's a digital circuit that has switching transients and two or three charge
pumps.  Unless the datasheet explicity says otherwise, the assumption should
be that good power supply bypass is required.  The fact that they explicitly
call for 1uF should be a big clue that something there matters more than
usual.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@183210 by olin piclist

face picon face
Vitaliy wrote:
> Yeah, it's great that you don't need external caps for charge pumps,
> but you end up overpaying $8 per IC compared to, say, MAX221. Is it
> really worth it?

Since this is one-off and he's getting the samples for free, probably yes.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@183637 by olin piclist

face picon face
solarwind wrote:
> The thing also works perfectly
> without any capacitor at all,

As far as you can tell over the limited range of test conditions you have
applied to it.  Running it without a power supply cap is asking for trouble.
The likely symptom is that it works 99.9% of the time.

> but that's probably because I'm powering
> it from USB.

Probably not.

> since everyone keeps telling
> me to use 0.1 uF.

No they haven't.  I certainly haven't.  As I said before, 100nF bypass caps
are so 1990s.  If someone tells you that should be the standard value, you
should be careful about what other bad or outdated advice they may be
dispensing.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\16@193637 by Vitaliy

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Olin Lathrop wrote:
> Vitaliy wrote:
>> Olin, you haven't read the datasheet yourself, have you? It says
>> nothing about not using electrolytics.
>
> We're talking about power supply "bypass" or "decoupling" caps.

The OP was specifically asking about a decoupling cap for a MAX233A.


>  Basic
> electronics should be enough to assume that electrolytics are not suited
> for
> this application unless the datasheet specifically says so, and I expect
> it
> doesn't.  There is really no place left today for a 1uF electrolytic
> capacitor.

This is completely backwards. If Maxim doesn't want us to use electrolytics,
they should explicitly say so.


>> It says nothing about "low ESR", either. Any cap will do.
>
> It may not say anything about ESR, but this gets to the level of obvious
> unless the datasheet specifically says otherwise.

Most datasheets would specifically tell you whether a low-ESR cap is
required. For instance, Microchip goes to great pains to explain this when
it matters (I recently read an entire app note devoted to this issue).


> At some point they have
> to rely on the person reading the datasheet to know at least a little
> about
> electronics.  Keep in mind that even though a electrolytic would not be
> violating the datasheet if taken literally, neither would a ceramic, and
> there are plenty of good reasons to use a ceramic instead of a
> electrolytic
> in this case.

If it ain't forbidden, it is permitted. If a non-electrolytic low-ESR cap is
required, it is the manufacturer's responsibility to tell me so. This has
nothing to do with my level of knowledge of electronics. The IC in most
cases is a black box, and I trust the mfr to tell me what to hook up to it.


{Quote hidden}

I would have no problem if you said that SW should just buy a bunch of
ceramic 1uF caps, and forget about the whole thing. But woe unto you, for ye
lade newbies with burdens grievous to be borne unnecessarily.

Vitaliy

2009\04\16@195504 by peter green

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face

>
> We're talking about power supply "bypass" or "decoupling" caps.  Basic
> electronics should be enough to assume that electrolytics are not suited for
> this application unless the datasheet specifically says so, and I expect it
> doesn't.
It doesn't actually seem (btw I hate the way maxim datasheets cover so
many bloody parts that is is hard to tell what stuff is intended for
your chip) to explicitly specify the cap is required it just shows it in
the typical operating circuit. In that circuit it is shown as a
polarised capacitor which (absent further information) would seem to
indicate to me that an electrolytic is acceptable.

2009\04\16@195610 by Bob Blick

face
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On Thu, 16 Apr 2009 18:30:46 -0400, "Olin Lathrop"
<TakeThisOuTolin_piclistEraseMEspamspam_OUTembedinc.com> said:

{Quote hidden}

I'm going with Vitaliy here. The 1uF requirement is for bulk
capacitance, not low ESR. Any cap will work perfectly fine. The
resistance in the switching elements is higher than the ESR of the worst
electrolytic.

Cheerful regards,
Bob

--
http://www.fastmail.fm - mmm... Fastmail...

2009\04\16@212952 by Xiaofan Chen

face picon face
On Fri, Apr 17, 2009 at 7:56 AM, Bob Blick <RemoveMEbobblickspamTakeThisOuTftml.net> wrote:
>
> I'm going with Vitaliy here. The 1uF requirement is for bulk
> capacitance, not low ESR. Any cap will work perfectly fine.
> The resistance in the switching elements is higher than the
> ESR of the worst electrolytic.

Sorry I do not quite understand you. What do you refer
by "switching elements" here?

The discussion topic here is the power supply "bypass"
or "decoupling" caps and I agree with Olin that in general
electrolytic is not recommended in this application. It
might work in some cases.

The Maxim datasheet shows a polarized capacitor.
I would assume that they mean tantalum capacitor
or similar. Actually I would think a ceramic capacitor
is more suitable nowadays.

--
Xiaofan http://mcuee.blogspot.com

2009\04\16@214449 by Xiaofan Chen

face picon face
On Fri, Apr 17, 2009 at 9:29 AM, Xiaofan Chen <xiaofancEraseMEspam.....gmail.com> wrote:

> The discussion topic here is the power supply "bypass"
> or "decoupling" caps and I agree with Olin that in general
> electrolytic is not recommended in this application. It
> might work in some cases.
>

Interestingly, Planet Analog just published a three part
article on this topic.
http://www.planetanalog.com/features/showArticle.jhtml?articleID=199905522

I still use mostly 100nF and 10nF ceramic (0603 or 0402) capacitors
for bypass. For some more power hungry ICs, I will typically put
1uF (0603 or 0805), or 10uF (1206) in parallel with the 100nF/10nF.
Even for bulk capacitor after the linear regulators, ceramic capacitors
are replacing tantalum capacitors and electrolytic capacitors due
to space constraint. The main problem is the high voltage (say 35V
or 50V) bulk capacitors for DC/DC converters, that is still the kingdom of
electrolytic capacitors most of the time. Even there I will put several
ceramic capacitors in parallel.

--
Xiaofan http://mcuee.blogspot.com

2009\04\16@225414 by solarwind

picon face
On Thu, Apr 16, 2009 at 9:44 PM, Xiaofan Chen <EraseMExiaofancspamgmail.com> wrote:
> Interestingly, Planet Analog just published a three part
> article on this topic.
> http://www.planetanalog.com/features/showArticle.jhtml?articleID=199905522

That's an interesting article, thanks!

2009\04\16@230952 by Bob Blick

face
flavicon
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Xiaofan Chen wrote:
> On Fri, Apr 17, 2009 at 7:56 AM, Bob Blick <RemoveMEbobblickEraseMEspamEraseMEftml.net> wrote:
>> I'm going with Vitaliy here. The 1uF requirement is for bulk
>> capacitance, not low ESR. Any cap will work perfectly fine.
>> The resistance in the switching elements is higher than the
>> ESR of the worst electrolytic.
>
> Sorry I do not quite understand you. What do you refer
> by "switching elements" here?

The on resistance of the charge pump transistors. It defines the peak
current.

> The discussion topic here is the power supply "bypass"
> or "decoupling" caps and I agree with Olin that in general
> electrolytic is not recommended in this application. It
> might work in some cases.

Why shouldn't it work in any case? It's a low speed device and needs
bulk capacitance.

> The Maxim datasheet shows a polarized capacitor.
> I would assume that they mean tantalum capacitor
> or similar. Actually I would think a ceramic capacitor
> is more suitable nowadays.

Why assume it's a tantalum capacitor? Why not assume it's an electrolytic?

I realize that we're talking about Maxim, but if you look at the TI
datasheet for the MAX232, it says on page 7, "Nonpolarized ceramic caps
are acceptable. If polarized tantalum or electrolytic capacitors are
used, they should be connected as shown" with the diagram showing
polarity marks on the appropriate ends.

So as far as TI is concerned, any of the three types of capacitor is OK
with them. And I say the choice of 1uF is for bulk capacitance, and that
their allowance of any type of capacitor backs that statement up.

Cheerful regards,

Bob

2009\04\16@231820 by Michael Hagen

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Speaking on Decoupling Caps (this is like an "Which is the BEST Oil Thread
on my Motorcycle Groups", just keeps going),

In the late 80's I worked for Philips Ultasound Corp.  We had the best HP
Impedance analyzer money could buy!

I could not believe how good those cheap (OK , inexpensieve) 1uf
Electrolytics were as far a ESR!
Yes the ones from Digikey and Mouser, like 1uF/50V.

I bitched about buying standard run of the mill capacitors for a machine
that had high power drivers for the Ultrasound Tranducers.  Everything was
very critical, to image, the bandwidth of our array drivers was from about
700Khz all the way to 14 Mhz.  These driver modules ended up being ceramic
hybrid modules made in Israel.  Lots of individual FET drivers, because of
the focusing of the ultrasound transducer.  Lots of noise!
Hey, the best part was when we had demo in the lab at looking at babies in
mom, facinating!

The .1uf ceramics were going down in impedance until about 100Mhz, would dip
(bottom out) and start up because of lead and self inductance.  We soldered
everything to copper pcb with no lead length to clamp in the analyser.
I wish I could remember the exact numbers, but in the mili ohms, often a
cheap electrolytic would really supprise.

So a .1uf in parallel with the electrolytic did well.  Of couse, lots of
Spicing, and a really good Analog Engineer was the key.  Not me, another
retiree!

I never got to work for many places that had the instruments and gave you
the time to do such tests.

I think PCB layout was much more important than the problems we had with
components?

But that is just another opinion from a real old fart!

Mikey, remembering the HP Impedance Analyzer with fond affection!





2009\04\17@010305 by Xiaofan Chen

face picon face
On Fri, Apr 17, 2009 at 11:18 AM, Michael Hagen <RemoveMEpicdogspam_OUTspamKILLspamdslextreme.com> wrote:
>
> Mikey, remembering the HP Impedance Analyzer with fond affection!
>

I like the HP4194 I used in my previous job.

--
Xiaofan http://mcuee.blogspot.com

2009\04\17@011318 by Xiaofan Chen

face picon face
On Fri, Apr 17, 2009 at 11:10 AM, Bob Blick <RemoveMEbobblickTakeThisOuTspamspamftml.net> wrote:
> Why assume it's a tantalum capacitor? Why not assume it's an electrolytic?
>
> I realize that we're talking about Maxim, but if you look at the TI
> datasheet for the MAX232, it says on page 7, "Nonpolarized ceramic caps
> are acceptable. If polarized tantalum or electrolytic capacitors are
> used, they should be connected as shown" with the diagram showing
> polarity marks on the appropriate ends.
>
> So as far as TI is concerned, any of the three types of capacitor is OK
> with them. And I say the choice of 1uF is for bulk capacitance, and that
> their allowance of any type of capacitor backs that statement up.
>

Even if you are right here that electrolytic can be used, in any case,
I have not seen any design using a low voltage low value electrolytic
(1uF is low value for electrolytic) in the past 10 years as electronics
design engineer.

I have only used 1uF electrolytic once when I was designing some
universal input sensors (level and photoelectric). The voltage input
is 12-240V DC and 20-240V AC.

Other than that, for low voltage application, you typically use ceramic
and tantalum or similar (if ceramic is not good).



--
Xiaofan http://mcuee.blogspot.com

2009\04\17@020634 by William \Chops\ Westfield

face picon face

On Apr 16, 2009, at 10:13 PM, Xiaofan Chen wrote:

> I have not seen any design using a low voltage low value electrolytic
> (1uF is low value for electrolytic) in the past 10 years as  
> electronics
> design engineer.

I see them all the time.  Mostly attached to MAX232-type rs232 drivers  
on hobbyist devices (through-hole construction still being seen as an  
advantage, and high-value ceramic (1uF is relatively high value for a  
ceramic) being mostly SMT.)  (Although I have some 100uF 10V ceramics  
caps in 2022 smt package; a bit mind-blowing...)

http://www.sparkfun.com/commerce/images/products/28PinPicBoard-01-L_i_ma.jpg

BillW

2009\04\17@032526 by Xiaofan Chen

face picon face
On Fri, Apr 17, 2009 at 2:06 PM, William "Chops" Westfield
<EraseMEwestfwspamspamspamBeGonemac.com> wrote:
>
> On Apr 16, 2009, at 10:13 PM, Xiaofan Chen wrote:
>
>> I have not seen any design using a low voltage low value electrolytic
>> (1uF is low value for electrolytic) in the past 10 years as
>> electronics design engineer.
>
> I see them all the time.  Mostly attached to MAX232-type rs232 drivers
> on hobbyist devices (through-hole construction still being seen as an
> advantage, and high-value ceramic (1uF is relatively high value for a
> ceramic) being mostly SMT.)  (Although I have some 100uF 10V ceramics
> caps in 2022 smt package; a bit mind-blowing...)
>
> http://www.sparkfun.com/commerce/images/products/28PinPicBoard-01-L_i_ma.jpg

You are right, there may be a lot of hobbyist design which is of different
requirement than what I have seen. I should have put "professional design"
or something similar.

--
Xiaofan http://mcuee.blogspot.com

2009\04\17@044040 by Alan B. Pearce

face picon face
Vitaliy wrote
>solarwind wrote:
>>I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
>> are the newer ones that require no external caps for the charge pumps.
>
>Yeah, it's great that you don't need external caps for charge pumps,
>but you end up overpaying $8 per IC compared to, say, MAX221.
>Is it really worth it?

And also as I remember from postings on this list previously, these chips
that do not need external capacitors use a higher internal switching
frequency on the charge pump, and people have found that creates EMC
problems.

2009\04\17@073804 by olin piclist

face picon face
Vitaliy wrote:
> Most datasheets would specifically tell you whether a low-ESR cap is
> required. For instance, Microchip goes to great pains to explain this
> when it matters (I recently read an entire app note devoted to this
> issue).

This doesn't mean everyone does.  The manufacturer can't possibly put
everything into a datasheet.  At some point they have to rely on common
sense and a little basic knowledge from the reader.

> If it ain't forbidden, it is permitted.

Then go ahead and use electroytics for bypassing.  When units fail and
customers complain, just tell them the datasheet didn't say anything against
using electrolytics.  I'm sure they'll understand.

> If a non-electrolytic low-ESR
> cap is required, it is the manufacturer's responsibility to tell me so.

Should they also tell you not to bend the pins too often, not to chew the
corners of the chip, not to put a 10ohm resistor in series with the power
supply?

> This has nothing to do with my level of knowledge of electronics.

Of course it does.  If you know nothing about electronics any PIC datasheet
is going to be over your head.  It's intended for a certain level of
audience.  Some knowledge has to be assumed.

{Quote hidden}

Actually I did tell him to get a bunch of 0805 1uF ceramic caps.

> But woe unto you,
> for ye lade newbies with burdens grievous to be borne unnecessarily.

Huh?  In this case I also explained why, partly because I don't like to just
give a answer, and partly because he asked why.  I don't understand your
beef here.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\17@074046 by olin piclist

face picon face
peter green wrote:
> It doesn't actually seem (btw I hate the way maxim datasheets cover so
> many bloody parts that is is hard to tell what stuff is intended for
> your chip) to explicitly specify the cap is required it just shows it in
> the typical operating circuit. In that circuit it is shown as a
> polarised capacitor which (absent further information) would seem to
> indicate to me that an electrolytic is acceptable.

I was taking Solarwind's word for it that the datasheet specified 1uF.  No,
I'm not going to chase down the datasheet just to answer a basic question.
Of course if he gave us incorrect information, then the resulting responses
could also be incorrect.

Note also that a polarized capacitor could mean tantalum, which has rather
different properties for that application than electrolytic.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\17@075101 by olin piclist

face picon face
Bob Blick wrote:
>> Sorry I do not quite understand you. What do you refer
>> by "switching elements" here?
>
> The on resistance of the charge pump transistors. It defines the peak
> current.

It defines the peak current of the charge pump perhaps, but not of the whole
chip.  It's a digital chip, so there can be other switching transients that
could be quite fast.

> Why shouldn't it work in any case? It's a low speed device and needs
> bulk capacitance.

You don't know that.  I agree part of the requirement is likely for bulk
capacitance.  Good engineering principles should indicate that a ceramic cap
is the right answer here.  At 1uF is satisfies the bulk capacitance
requirement because the datasheet says so, but it also will provide power
supply bypass for the high frequency transients if there are any.  Since we
can't tell for sure from the datasheet whether there are any, and basic
electronics tells it's at least reasonably possible, using a ceramic cap is
just good engineering.

Let's keep this in perspective.  I'm not advocating for a large or expensive
solution.  In fact, a ceramic 1uF SMD cap will be smaller, cheaper, more
reliable, and more rugged than any tantalum or electrolytic of suitable
rating.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\17@075854 by olin piclist

face picon face
William Chops" Westfield" wrote:
> 1uF is relatively high value for a ceramic

Not for a few years now, at least for normal logic voltages.  Take a look at
DigiKey, Mouser, etc.  You will see 1uF 10V readily and cheaply available.
In fact 1uF 10V 0805 ceramic caps will be cheaper than any 1uF electrolytic
or tantalum, and also smaller and more reliable.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\17@080425 by Xiaofan Chen

face picon face
On Fri, Apr 17, 2009 at 8:01 PM, Olin Lathrop <RemoveMEolin_piclistKILLspamspamembedinc.com> wrote:
> William Chops" Westfield" wrote:
>> 1uF is relatively high value for a ceramic
>
> Not for a few years now, at least for normal logic voltages.  Take a look at
> DigiKey, Mouser, etc.  You will see 1uF 10V readily and cheaply available.
> In fact 1uF 10V 0805 ceramic caps will be cheaper than any 1uF electrolytic
> or tantalum, and also smaller and more reliable.
>

Indeed. I've been using 1uF 0805 since year 2004. I am now using
some 4u7 1206 ceramic as well.

--
Xiaofan http://mcuee.blogspot.com

2009\04\17@082343 by peter green

flavicon
face

> Interestingly, Planet Analog just published a three part
> article on this topic.
> www.planetanalog.com/features/showArticle.jhtml?articleID=199905522
>  
Hmm, I was  under the impression that tantalum was lower ESR than
electrolytic and i've seen datasheets specify "ceramic or tantalum"
which reinforces this view. But the table in that article puts tantalum
as a higher ESR than electrolytic.

Can anyone clarify? was I wrong? is this something that has changed with
recent technical developments?

2009\04\17@083134 by Sean Breheny

face picon face
Olin wrote about what Bob said:
>> But woe unto you,
>> for ye lade newbies with burdens grievous to be borne unnecessarily.
>
> Huh?  In this case I also explained why, partly because I don't like to just
> give a answer, and partly because he asked why.  I don't understand your
> beef here.

I think he is referring (loosely and jokingly) to Matthew 23:4 "They
tie up heavy burdens 3 (hard to carry) and lay them on people's
shoulders, but they will not lift a finger to move them.", where Jesus
refers to the way the Pharisees wrote long lists of regulations for
people to follow, then ignored the more fundamental truths of God's
law (mercy, justice, helping others, etc.)

http://www.usccb.org/nab/bible/matthew/matthew23.htm

Sean

2009\04\17@083444 by Sean Breheny

face picon face
I do not know about the ESR of tantalum vs Al electrolytic, but I did
recently learn that high value SMT ceramic caps often have a large
change in capacitance with voltage. For example, I have some 2.2uF
100V 1210-size SMT caps which are only around 1.6uF at 50V bias. So,
caution must be exercised when using these "magical" newer high value
ceramic caps that you provide enough of them to get the minimum
capacitance you need. It seems to be especially a problem for higher
voltage ones, but I think it happens to a lesser degree even with the
16V and 25V ones.

Sean


On Fri, Apr 17, 2009 at 8:23 AM, peter green <plugwashSTOPspamspamspam_OUTp10link.net> wrote:
{Quote hidden}

>

2009\04\17@092044 by John Day

flavicon
face
At 08:01 AM 4/17/2009, Olin Lathrop wrote:
>William Chops" Westfield" wrote:
> > 1uF is relatively high value for a ceramic
>
>Not for a few years now, at least for normal logic voltages.  Take a look at
>DigiKey, Mouser, etc.  You will see 1uF 10V readily and cheaply available.
>In fact 1uF 10V 0805 ceramic caps will be cheaper than any 1uF electrolytic
>or tantalum, and also smaller and more reliable.

So very true. For anything up to about 10uF at low voltage I now use
ceramic because of the size and the high frequency performance. Up to
5V is can pretty much always use an 0603 package which helps a lot.

On things like CPU's and FPGA's, especially with 1.2, 1.5, 1.8 or
3.3V supplies it is common to need a mix of bypass caps from 1nF to
1uF for each supply rail. For the switch mode regulators it is often
necessary or desirable to use ceramics up to 22uF or more.

In my current designs I don't think I have an electrolytic below 39uF
or 47uF. For bulk energy tantalums have become less attractive as
prices have risen and reliability has not. A combination of high
value ceramics and electrolytics is likely to be equal in
performance, lower in cost and have equal or better reliability.

John

2009\04\17@092301 by Mike Harrison

flavicon
face
On Fri, 17 Apr 2009 08:34:42 -0400, you wrote:

>I do not know about the ESR of tantalum vs Al electrolytic, but I did
>recently learn that high value SMT ceramic caps often have a large
>change in capacitance with voltage. For example, I have some 2.2uF
>100V 1210-size SMT caps which are only around 1.6uF at 50V bias. So,
>caution must be exercised when using these "magical" newer high value
>ceramic caps that you provide enough of them to get the minimum
>capacitance you need. It seems to be especially a problem for higher
>voltage ones, but I think it happens to a lesser degree even with the
>16V and 25V ones.

I think this is moslty an issue with caps with '5' in the dielectric type, usually Y5V, which also
have poor stability with temperature, and I've also found they can be slighly piezoelectric,
emitting audible noise under high DI/DT situations.
'5' series dielectric ceramic caps are best avoided in anything vaguely critical (like if you care
about a 50% capacitance change), but are probably OK for non-critical decoupling at normal
temperatures.

2009\04\17@093656 by olin piclist

face picon face
John Day wrote:
> In my current designs I don't think I have an electrolytic below 39uF
> or 47uF. For bulk energy tantalums have become less attractive as
> prices have risen and reliability has not. A combination of high
> value ceramics and electrolytics is likely to be equal in
> performance, lower in cost and have equal or better reliability.

I agree.  I use electrolytics when the combination of capacitance and
voltage is out of range of ceramics.

Since switching power supplies are the norm nowadays and it seems every
board has a few, the demands on large bulk storage caps has changed.
Several times I've had to put electrolytic caps in parallel not to get the
extra capacitance, but to not exceed the ripple current spec.  Ripple
current is a serious stress on capacitors used in switching power supplies,
and all electrolytics are definitely not created equal.  This is one of the
few places I often specify particular models.  I used to use the Panasonic
FC series in these applications extensively, but the new FK series has even
better specs for ESR and ripple current tolerance.  (ESR and ripple current
tolerance generally go together since it's typically not the ripple current
itself that destroys a cap, but the heating it causes)


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\17@100043 by John Day

flavicon
face
At 09:22 AM 4/17/2009, Mike Harrison wrote:
{Quote hidden}

Good points. You really need to determine what is the minimum
capacitance you require in the high value parts and then study the
manufacturers data carefully to make sure you get what you need.

There is really nothing magical about these parts, you still have to
carefully read the data sheet to understand what you are getting!
This WikiPedia page gives an excellent summary of what you can
expect:" http://en.wikipedia.org/wiki/EIA_Class_2_dielectric from
various dielectrics. It is not the 5 is the problem, it is the T, U
or V on the end! You should only go for things like Y5V where space
is an issue and you can be sure to get what capacitance you need.
X7R, or even X5R is generally the better choice, as long as you have
room for the higher values which do get big.

Most of the class 2 dielectrics are based on Barium Titanate and have
very high dielectric constants, hence why the can become piezo
transducers under those high di/dt conditions. They can also
introduce microhpnic noise under ihgh vibration conditions too.

I once saw an audio system which used that class of capacitor and the
engineer who designed it couldn't understand why he could get
acoustic feedback when he moved the board so that it was exposed to the audio.

John



>

2009\04\17@101952 by Bob Axtell

face picon face
I recommend following the datasheet closely, especially for these
components. I tried to use those parts a number oif years ago and was
unable to get the product to pass FCC radiation
tests. I had to drop back to a part that used 4 0.1uF for switching.

--Bob

On Wed, Apr 15, 2009 at 5:03 PM, solarwind <spamBeGonex.solarwind.xSTOPspamspamEraseMEgmail.com> wrote:
> I just sampled some MAX233A chips (TTL <---> RS-232 drivers). These
> are the newer ones that require no external caps for the charge pumps.
> However, the data sheet says to use a 1 uF capacitor from VCC to VDD.
> Why 1 uF? I have none of these. Would a 0.1 uF cermic cap work just as
> well or is there some weird requirement that it has to be 1 uf?
>
> -- [ solarwind ] --
> -

2009\04\17@105341 by John Day

flavicon
face
At 09:39 AM 4/17/2009, Olin Lathrop wrote:
>John Day wrote:
> > In my current designs I don't think I have an electrolytic below 39uF
> > or 47uF. For bulk energy tantalums have become less attractive as
> > prices have risen and reliability has not. A combination of high
> > value ceramics and electrolytics is likely to be equal in
> > performance, lower in cost and have equal or better reliability.
>
>I agree.  I use electrolytics when the combination of capacitance and
>voltage is out of range of ceramics.
>
>Since switching power supplies are the norm nowadays and it seems every
>board has a few, the demands on large bulk storage caps has changed.

Indeed. My current design is a pair of boards that comprise
essentially a PowerPC & FPGA based CPU board and a rather complex
interface and analog control board. There are a total of about 15
regulators, and only a couple of those are LDO's where we need low
current at low voltage.

Especially as SM regulator frequencies increase we are naturally
using more ceramic and less tantalum. It was only a few years ago
that most switch mode regulators ran at 25 or 50kHz. Now even high
current regulators run at 250kHz or more and for the lower currents
it is not uncommon to go to 1.6 or even 3.2MHz. Oh how delightfully
small they have gotten.

>Several times I've had to put electrolytic caps in parallel not to get the
>extra capacitance, but to not exceed the ripple current spec.  Ripple
>current is a serious stress on capacitors used in switching power supplies,
>and all electrolytics are definitely not created equal.

Have you ever noticed that many regulators on PC motherboards use
three or four electrolytic capacitors in parallel in the output.
Often they will have 4 caps, series inductor, and another 4 caps.
Just proves that MORE can be BETTER!

>   This is one of the
>few places I often specify particular models.  I used to use the Panasonic
>FC series in these applications extensively, but the new FK series has even
>better specs for ESR and ripple current tolerance.  (ESR and ripple current
>tolerance generally go together since it's typically not the ripple current
>itself that destroys a cap, but the heating it causes)

Of all of the time I spend choosing components I probably spend more
on things like power supply capacitors, especially electrolytics,
than on anything else. Heating in capacitors is fatal.

I agree about specifying particular models. I have gotten to the
point now where I have one type form Panasonic, one from United
Chemicon and one from NIC that make it onto my approved parts list.
But another difficulty right now is specifying electrolytics that are
also able to withstand the elevated temperatures required in RoHS /
Lead free soldering processes. We use some 1000uF 16V and 330uF 50V
SMT electro's and one of our contract manufacturers wants to hand
solder them because they are not rated for a 260C reflow cycle.

John



>********************************************************************
>Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
>(978) 742-9014.  Gold level PIC consultants since 2000.
>

2009\04\17@110344 by William \Chops\ Westfield

face picon face

On Apr 17, 2009, at 5:01 AM, Olin Lathrop wrote:

>> 1uF is relatively high value for a ceramic
>
> Not for a few years now, at least for normal logic voltages.  Take a  
> look at
> DigiKey, Mouser, etc.  You will see 1uF 10V readily and cheaply  
> available.

The rest of the paragraph was supposed to clarify "1uf is relatively  
high value for a through-hole ceramic cap."  Out of the 934 caps that  
digikey reports for in-stock 1uF ceramic caps, 44 are TH.

BillW

2009\04\17@135820 by peter green

flavicon
face
Bob Axtell wrote:
> I recommend following the datasheet closely, especially for these
> components.
The trouble is the datasheet is crap. No information on what sort of
caps to use, no layout guidelines and afaict (I might have missed
something in the tables of mostly irrelevent information) no information
on what the peak currents and frequencies of the charge pump are (which
you would need to work such things out from first principles)

2009\04\17@141537 by Sean Breheny

face picon face
I agree that this depends greatly on the type of dielectric used, but
I've seen the problem with X7R types, too, at least for ones which
have a very high voltage rating for a small package (2.2uF 100V 1210
size in my case).

Sean


On Fri, Apr 17, 2009 at 10:01 AM, John Day <KILLspamjohn.dayspamBeGonespamsiliconrailway.com> wrote:
{Quote hidden}

2009\04\17@143629 by olin piclist

face picon face
William Chops" Westfield" wrote:
> The rest of the paragraph was supposed to clarify "1uf is relatively
> high value for a through-hole ceramic cap."

So?  Thru hole caps haven't been relevant in years.  You can stick to point
to point wiring using tube socket eyelets too, but the rest of the world has
moved on long ago.

> Out of the 934 caps that
> digikey reports for in-stock 1uF ceramic caps, 44 are TH.

That's probably because there are some existing old designs that have been
qualified and continue to be produced.  Even those are clearly a small
fraction of the capacitor market.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\17@150525 by John Day

flavicon
face
At 02:39 PM 4/17/2009, Olin Lathrop wrote:
>William Chops" Westfield" wrote:
> > The rest of the paragraph was supposed to clarify "1uf is relatively
> > high value for a through-hole ceramic cap."
>
>So?  Thru hole caps haven't been relevant in years.  You can stick to point
>to point wiring using tube socket eyelets too, but the rest of the world has
>moved on long ago.

LOL

But of course I go into our factory and I see lots and lots of
through hole ceramic caps, but they have ratings like 5kV, 15kV and
the like. I wish I could find some nice 15-20kV rated ceramics in SMT
that would handle immersion in oil.


> > Out of the 934 caps that
> > digikey reports for in-stock 1uF ceramic caps, 44 are TH.
>
>That's probably because there are some existing old designs that have been
>qualified and continue to be produced.  Even those are clearly a small
>fraction of the capacitor market.

A VERY VERY small fraction of the market.

Some products we have been building for 15-20 years are still done
through hole, but we are moving them to SMT because we can no longer
get parts we need.

As time goes on even the average home experimenter will need to adapt
to SMT, it isn't hard, I have used pretty much all SMT even for home
built hobby stuff for most of the last 10 years. But Olin I htink
sometimes that people like you and I are the exception, plenty of the
folk on this list are frightened by SMT and lots of them wont even try it.


John


2009\04\17@154524 by solarwind

picon face
On Fri, Apr 17, 2009 at 7:40 AM, Olin Lathrop <EraseMEolin_piclistspamEraseMEembedinc.com> wrote:
> not to put a 10ohm resistor in series with the power
> supply?

Wait, what's wrong with that? (I'm a total noob to analog electronics.)



---


Holy crap, do my posts really cause THIS much trouble?!?!

2009\04\17@164130 by olin piclist

face picon face
solarwind wrote:
>> not to put a 10ohm resistor in series with the power
>> supply?
>
> Wait, what's wrong with that? (I'm a total noob to analog electronics.)

What does Ohm's law have to say about the supply voltage to the part as the
part draws current when there is 10 ohms between it and the power supply?
How much current causes the supply to dip below specs?  How much current
does the part draw?

That last question is the zinger.  Explain why or take a guess at it.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.

2009\04\18@135901 by Kenneth Lumia

picon face

> Hmm, I was  under the impression that tantalum was
> lower ESR than
> electrolytic and i've seen datasheets specify
> "ceramic or tantalum"
> which reinforces this view. But the table in that
> article puts tantalum
> as a higher ESR than electrolytic.
>
> Can anyone clarify? was I wrong? is this something
> that has changed with
> recent technical developments?

Peter,

Never rely on a "generalized" table.  Tantalum caps can
have extremely low ESR, depending on the manufacturer
and series.  Some have internal fuses in series which
raises the ESR (and negates the reason for using tants
in the first place). You must read / understand /
interpret the spec sheets for all parts in order to
choose correctly. Manufacturers typically are poor at
rating their caps, especially for items such as
temperature rise and ripple current. All of the above
being said, E-Caps typically have highest ESR (violent
hand waving now in progress). Large value (multi-uF)
ceramic caps have gotten much cheaper in recent years,
have decent ESR and are often preferred over tantalums
for various reasons.

Ken

2009\04\21@051931 by Vitaliy

flavicon
face
Sean Breheny wrote:
Olin wrote about what Bob said:
>> But woe unto you,
>> for ye lade newbies with burdens grievous to be borne unnecessarily.
>
> Huh? In this case I also explained why, partly because I don't like to
> just
> give a answer, and partly because he asked why. I don't understand your
> beef here.

>I think he is referring (loosely and jokingly) to Matthew 23:4

Hmm, I thought I was misquoting Luke... yup, Luke 11:46:

"And he said, Woe unto you also, ye lawyers! for ye lade men with burdens
grievous to be borne, and ye yourselves touch not the burdens with one of
your fingers."

Same idea. :-)

Vitaliy

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