Why do we use polarized capacitors?Are tantalum capacitors safe for use in new designs?Why does the LM1117 data sheet specifically specify tantalum capacitors?Amplifier capacitorsWhy do some capacitors leak and other capacitors hardly leak at all?What are these electrolytic capacitors?Why are capacitors with large values are manufactured polarized?Is it safe to use series polarized capacitors to form non-polarized capacitors to be used for higher rated voltage?Unpolarized Capacitors in place of Polarized onesWhy is this power cable sometimes polarized and sometimes not?Can I use polarized capacitors in a location where they shouldn't be polarized?Non-Polarized Electrolytic Capacitor Replacement
As an international instructor, should I openly talk about my accent?
Solving a quadratic equation by completing the square
How to have a sharp product image?
Is there any official lore on the Far Realm?
Is there a way to generate a list of distinct numbers such that no two subsets ever have an equal sum?
How can I get this effect? Please see the attached image
What makes accurate emulation of old systems a difficult task?
Don’t seats that recline flat defeat the purpose of having seatbelts?
How do I deal with a coworker that keeps asking to make small superficial changes to a report, and it is seriously triggering my anxiety?
Can't get 5V 3A DC constant
Could the terminal length of components like resistors be reduced?
How exactly does Hawking radiation decrease the mass of black holes?
What does the integral of a function times a function of a random variable represent, conceptually?
Why do games have consumables?
Minor Revision with suggestion of an alternative proof by reviewer
Is there really no use for MD5 anymore?
Why did C use the -> operator instead of reusing the . operator?
Elements that can bond to themselves?
How can I print the prosodic symbols in LaTeX?
Which big number is bigger?
How do I reattach a shelf to the wall when it ripped out of the wall?
Is the claim "Employers won't employ people with no 'social media presence'" realistic?
Critique of timeline aesthetic
How to fry ground beef so it is well-browned
Why do we use polarized capacitors?
Are tantalum capacitors safe for use in new designs?Why does the LM1117 data sheet specifically specify tantalum capacitors?Amplifier capacitorsWhy do some capacitors leak and other capacitors hardly leak at all?What are these electrolytic capacitors?Why are capacitors with large values are manufactured polarized?Is it safe to use series polarized capacitors to form non-polarized capacitors to be used for higher rated voltage?Unpolarized Capacitors in place of Polarized onesWhy is this power cable sometimes polarized and sometimes not?Can I use polarized capacitors in a location where they shouldn't be polarized?Non-Polarized Electrolytic Capacitor Replacement
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
I want to know if the polarized capacitor has some advantage that they are used in some circuits?
For example, in a schematic of the BISS001 PIR controller IC, in some places, a polarized capacitor is used and in some places a non-polarized capacitor one.
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Reference Docs:
- BISS001 datasheet
- HC-SR501 PIR MOTION DETECTOR datasheet
Grove - PIR Motion Sensor or EasyEDA link
What I've understand from your answers is why the electrolytic capacitors are used, and why these are polarized.
But the designers of this circuit could have used a non-polarized capacitor or even polarized tantalum capacitors. Is it true? As the (Grove - PIR Motion Sensor) module uses polarized tantalum capacitors.
I want to know if the polarized capacitors are being used for circuit protection or is there any other reason (regardless of the type of capacitor.)
Is there a problem if these capacitors are replaced with non-polarized capacitors in these circuits?
capacitor circuit-design polarity
$endgroup$
add a comment |
$begingroup$
I want to know if the polarized capacitor has some advantage that they are used in some circuits?
For example, in a schematic of the BISS001 PIR controller IC, in some places, a polarized capacitor is used and in some places a non-polarized capacitor one.
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Reference Docs:
- BISS001 datasheet
- HC-SR501 PIR MOTION DETECTOR datasheet
Grove - PIR Motion Sensor or EasyEDA link
What I've understand from your answers is why the electrolytic capacitors are used, and why these are polarized.
But the designers of this circuit could have used a non-polarized capacitor or even polarized tantalum capacitors. Is it true? As the (Grove - PIR Motion Sensor) module uses polarized tantalum capacitors.
I want to know if the polarized capacitors are being used for circuit protection or is there any other reason (regardless of the type of capacitor.)
Is there a problem if these capacitors are replaced with non-polarized capacitors in these circuits?
capacitor circuit-design polarity
$endgroup$
17
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
Apr 7 at 21:48
2
$begingroup$
Compare the prices of electrolytic caps with ceramic (or film) caps in the range of 10uF ~22uF (after taking bias voltage derating into consideration) and you will have one of the reasons.
$endgroup$
– Wesley Lee
Apr 7 at 21:54
$begingroup$
The very thin oxide layers, providing insulation for a certain polarity, provides a very compact energy storage module. Just view those useful electrolytic capacitors as early versions of self-assembled-nano-tech; the manufacturing process creates the very thin oxide layer: the oxide is GROWN or FORMED.
$endgroup$
– analogsystemsrf
Apr 7 at 22:01
4
$begingroup$
Is there a problem if these capacitors are replaced with non-polarized capacitors in this circuits?
-- no, there is no problem. But you may find it hard to find non-polarized capacitors of the same specification. Non-polarized capacitors are usually in the nF range and are usually rated for low voltage use (5V or less). If you want anything in the uF or mF and/or rated at tens of volts you will have to make do with polarized capacitors
$endgroup$
– slebetman
Apr 8 at 5:22
4
$begingroup$
@slebetman "Non-polarized capacitors are usually rated for low voltage use (5V or less)" - the reality is actually opposite of what you say.
$endgroup$
– Dmitry Grigoryev
Apr 8 at 8:03
add a comment |
$begingroup$
I want to know if the polarized capacitor has some advantage that they are used in some circuits?
For example, in a schematic of the BISS001 PIR controller IC, in some places, a polarized capacitor is used and in some places a non-polarized capacitor one.
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Reference Docs:
- BISS001 datasheet
- HC-SR501 PIR MOTION DETECTOR datasheet
Grove - PIR Motion Sensor or EasyEDA link
What I've understand from your answers is why the electrolytic capacitors are used, and why these are polarized.
But the designers of this circuit could have used a non-polarized capacitor or even polarized tantalum capacitors. Is it true? As the (Grove - PIR Motion Sensor) module uses polarized tantalum capacitors.
I want to know if the polarized capacitors are being used for circuit protection or is there any other reason (regardless of the type of capacitor.)
Is there a problem if these capacitors are replaced with non-polarized capacitors in these circuits?
capacitor circuit-design polarity
$endgroup$
I want to know if the polarized capacitor has some advantage that they are used in some circuits?
For example, in a schematic of the BISS001 PIR controller IC, in some places, a polarized capacitor is used and in some places a non-polarized capacitor one.
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Reference Docs:
- BISS001 datasheet
- HC-SR501 PIR MOTION DETECTOR datasheet
Grove - PIR Motion Sensor or EasyEDA link
What I've understand from your answers is why the electrolytic capacitors are used, and why these are polarized.
But the designers of this circuit could have used a non-polarized capacitor or even polarized tantalum capacitors. Is it true? As the (Grove - PIR Motion Sensor) module uses polarized tantalum capacitors.
I want to know if the polarized capacitors are being used for circuit protection or is there any other reason (regardless of the type of capacitor.)
Is there a problem if these capacitors are replaced with non-polarized capacitors in these circuits?
capacitor circuit-design polarity
capacitor circuit-design polarity
edited Apr 8 at 18:55
JakeGould
1155
1155
asked Apr 7 at 21:36
hamid mousavihamid mousavi
11116
11116
17
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
Apr 7 at 21:48
2
$begingroup$
Compare the prices of electrolytic caps with ceramic (or film) caps in the range of 10uF ~22uF (after taking bias voltage derating into consideration) and you will have one of the reasons.
$endgroup$
– Wesley Lee
Apr 7 at 21:54
$begingroup$
The very thin oxide layers, providing insulation for a certain polarity, provides a very compact energy storage module. Just view those useful electrolytic capacitors as early versions of self-assembled-nano-tech; the manufacturing process creates the very thin oxide layer: the oxide is GROWN or FORMED.
$endgroup$
– analogsystemsrf
Apr 7 at 22:01
4
$begingroup$
Is there a problem if these capacitors are replaced with non-polarized capacitors in this circuits?
-- no, there is no problem. But you may find it hard to find non-polarized capacitors of the same specification. Non-polarized capacitors are usually in the nF range and are usually rated for low voltage use (5V or less). If you want anything in the uF or mF and/or rated at tens of volts you will have to make do with polarized capacitors
$endgroup$
– slebetman
Apr 8 at 5:22
4
$begingroup$
@slebetman "Non-polarized capacitors are usually rated for low voltage use (5V or less)" - the reality is actually opposite of what you say.
$endgroup$
– Dmitry Grigoryev
Apr 8 at 8:03
add a comment |
17
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
Apr 7 at 21:48
2
$begingroup$
Compare the prices of electrolytic caps with ceramic (or film) caps in the range of 10uF ~22uF (after taking bias voltage derating into consideration) and you will have one of the reasons.
$endgroup$
– Wesley Lee
Apr 7 at 21:54
$begingroup$
The very thin oxide layers, providing insulation for a certain polarity, provides a very compact energy storage module. Just view those useful electrolytic capacitors as early versions of self-assembled-nano-tech; the manufacturing process creates the very thin oxide layer: the oxide is GROWN or FORMED.
$endgroup$
– analogsystemsrf
Apr 7 at 22:01
4
$begingroup$
Is there a problem if these capacitors are replaced with non-polarized capacitors in this circuits?
-- no, there is no problem. But you may find it hard to find non-polarized capacitors of the same specification. Non-polarized capacitors are usually in the nF range and are usually rated for low voltage use (5V or less). If you want anything in the uF or mF and/or rated at tens of volts you will have to make do with polarized capacitors
$endgroup$
– slebetman
Apr 8 at 5:22
4
$begingroup$
@slebetman "Non-polarized capacitors are usually rated for low voltage use (5V or less)" - the reality is actually opposite of what you say.
$endgroup$
– Dmitry Grigoryev
Apr 8 at 8:03
17
17
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
Apr 7 at 21:48
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
Apr 7 at 21:48
2
2
$begingroup$
Compare the prices of electrolytic caps with ceramic (or film) caps in the range of 10uF ~22uF (after taking bias voltage derating into consideration) and you will have one of the reasons.
$endgroup$
– Wesley Lee
Apr 7 at 21:54
$begingroup$
Compare the prices of electrolytic caps with ceramic (or film) caps in the range of 10uF ~22uF (after taking bias voltage derating into consideration) and you will have one of the reasons.
$endgroup$
– Wesley Lee
Apr 7 at 21:54
$begingroup$
The very thin oxide layers, providing insulation for a certain polarity, provides a very compact energy storage module. Just view those useful electrolytic capacitors as early versions of self-assembled-nano-tech; the manufacturing process creates the very thin oxide layer: the oxide is GROWN or FORMED.
$endgroup$
– analogsystemsrf
Apr 7 at 22:01
$begingroup$
The very thin oxide layers, providing insulation for a certain polarity, provides a very compact energy storage module. Just view those useful electrolytic capacitors as early versions of self-assembled-nano-tech; the manufacturing process creates the very thin oxide layer: the oxide is GROWN or FORMED.
$endgroup$
– analogsystemsrf
Apr 7 at 22:01
4
4
$begingroup$
Is there a problem if these capacitors are replaced with non-polarized capacitors in this circuits?
-- no, there is no problem. But you may find it hard to find non-polarized capacitors of the same specification. Non-polarized capacitors are usually in the nF range and are usually rated for low voltage use (5V or less). If you want anything in the uF or mF and/or rated at tens of volts you will have to make do with polarized capacitors$endgroup$
– slebetman
Apr 8 at 5:22
$begingroup$
Is there a problem if these capacitors are replaced with non-polarized capacitors in this circuits?
-- no, there is no problem. But you may find it hard to find non-polarized capacitors of the same specification. Non-polarized capacitors are usually in the nF range and are usually rated for low voltage use (5V or less). If you want anything in the uF or mF and/or rated at tens of volts you will have to make do with polarized capacitors$endgroup$
– slebetman
Apr 8 at 5:22
4
4
$begingroup$
@slebetman "Non-polarized capacitors are usually rated for low voltage use (5V or less)" - the reality is actually opposite of what you say.
$endgroup$
– Dmitry Grigoryev
Apr 8 at 8:03
$begingroup$
@slebetman "Non-polarized capacitors are usually rated for low voltage use (5V or less)" - the reality is actually opposite of what you say.
$endgroup$
– Dmitry Grigoryev
Apr 8 at 8:03
add a comment |
3 Answers
3
active
oldest
votes
$begingroup$
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Electrically speaking, non-polarized capacitor is always better than a polarized one. Yes, you can always replace with a non-polarized capacitor with exactly same rating.
But there is an assumption hidden here:Provided you can find one that's physically small enough to fit on your board and cheap enough to fit in your budget.
And the fact that you can't is the only reason we use polarized caps.
I assume that, if we ever learn to make non-polarized caps that are as cheap and dense (capacity-per-volume) as electrolytic ones, the polarized capacitors will vanish.
Side note - voltage and capacitance are not the only electrical parameters of a capacitor. They would suffice for an ideal capacitor, but real world brings other, ugly metrics. Like ESR, capacity coefficient with temperature or voltage, frequency response, etc. Circuits designed around quirks of particular tech can fail if the substitute differs there. Even being too good can cause trouble, eg. high-ESR caps naturally keep peak current in check so substituting with a theoretically superior low-ESR part can cause the whole thing to blow up. Adding ESR is trivial - but that's no longer a drop-in replacement, but rather a circuit redesign. So we don't replace electrolytics with something else not because polarization is important, it's just a nuisance. We keep them because of many other parameters, less obvious than C, V and polarization.
$endgroup$
2
$begingroup$
One thing that should also be noted is that in applications where the frequency response of the capacitor is important, you can't just replace one type with another, since they work well at different frequency ranges. Examples are e.g. noise filters.
$endgroup$
– nshct
Apr 8 at 21:22
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
Apr 8 at 21:25
$begingroup$
Suggestion: add to your answer a link about ESR : avnet.com/wps/portal/abacus/resources/engineers-insight/article/…
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
$begingroup$
The physical size of a capacitor is a function of the thickness of the dielectric (among other things).
Early on, it was discovered that the oxides of certain metals (aluminum and tantalum in particular) made good dielectrics, and could be made very thin through a chemical process — orders of magnitude thinner than other dielectrics such as waxed/oiled paper and plastic film. Therefore, the electrolytic capacitor was invented to provide high capacitance in a reasonable volume.
Unfortunately, the chemical process requires that the voltage across the capacitor must have only a single polarity, so these capacitors are "polarized". Reversing the polarity degrades and eventually destroys the oxide layer. It's something we just have to live with in order to take advantage of this technology.
The ability to produce high-value capacitors in nonpolarized technologies such as multilayer ceramic means that it is now possible to use them where only a polarized capacitor would have been previously available. There is generally no problem with making this substitution, although you may need to consider some of the quirks of the technology you're switching to.
For example, some high-K (high dielectric constant) ceramics exhibit significant capacitance changes with voltage. This might be acceptable in a coupling or bypass application, but completely unacceptable in a filter design.
$endgroup$
1
$begingroup$
There is a specific use case where replacing tantalum devices with MLCC parts can have unfortunate effects: at the output of some (older) LDO regulators which require a certain minimum output ESR. It can be done, but some care is necessary.
$endgroup$
– Peter Smith
Apr 8 at 9:03
$begingroup$
Very nice answer! I'm trying to figure out if asking "Why does the chemical process used to make capacitor dielectrics from oxides of certain metals (aluminum and tantalum in particular) require that the voltage across the capacitor must have only a single polarity?" but I'm not confident it will be on topic. Is there any chance you could add a hint here?
$endgroup$
– uhoh
Apr 8 at 10:28
add a comment |
$begingroup$
Since you mention protection I'll add that polarized caps should not be used for reverse polarity protection. They will react on a reverse voltage very slowly (seconds or minutes), while typical sensitive components which are worth protecting will be dead within milliseconds. And once a polarized cap starts to absorb the reverse voltage, it may vent, explode or catch fire which (apart from the obvious problem with smoke and fire) can make it non-conductive again, exposing your circuit to the reverse voltage once more.
$endgroup$
$begingroup$
Good point here.
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
Your Answer
StackExchange.ifUsing("editor", function ()
return StackExchange.using("schematics", function ()
StackExchange.schematics.init();
);
, "cicuitlab");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "135"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f431310%2fwhy-do-we-use-polarized-capacitors%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Electrically speaking, non-polarized capacitor is always better than a polarized one. Yes, you can always replace with a non-polarized capacitor with exactly same rating.
But there is an assumption hidden here:Provided you can find one that's physically small enough to fit on your board and cheap enough to fit in your budget.
And the fact that you can't is the only reason we use polarized caps.
I assume that, if we ever learn to make non-polarized caps that are as cheap and dense (capacity-per-volume) as electrolytic ones, the polarized capacitors will vanish.
Side note - voltage and capacitance are not the only electrical parameters of a capacitor. They would suffice for an ideal capacitor, but real world brings other, ugly metrics. Like ESR, capacity coefficient with temperature or voltage, frequency response, etc. Circuits designed around quirks of particular tech can fail if the substitute differs there. Even being too good can cause trouble, eg. high-ESR caps naturally keep peak current in check so substituting with a theoretically superior low-ESR part can cause the whole thing to blow up. Adding ESR is trivial - but that's no longer a drop-in replacement, but rather a circuit redesign. So we don't replace electrolytics with something else not because polarization is important, it's just a nuisance. We keep them because of many other parameters, less obvious than C, V and polarization.
$endgroup$
2
$begingroup$
One thing that should also be noted is that in applications where the frequency response of the capacitor is important, you can't just replace one type with another, since they work well at different frequency ranges. Examples are e.g. noise filters.
$endgroup$
– nshct
Apr 8 at 21:22
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
Apr 8 at 21:25
$begingroup$
Suggestion: add to your answer a link about ESR : avnet.com/wps/portal/abacus/resources/engineers-insight/article/…
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
$begingroup$
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Electrically speaking, non-polarized capacitor is always better than a polarized one. Yes, you can always replace with a non-polarized capacitor with exactly same rating.
But there is an assumption hidden here:Provided you can find one that's physically small enough to fit on your board and cheap enough to fit in your budget.
And the fact that you can't is the only reason we use polarized caps.
I assume that, if we ever learn to make non-polarized caps that are as cheap and dense (capacity-per-volume) as electrolytic ones, the polarized capacitors will vanish.
Side note - voltage and capacitance are not the only electrical parameters of a capacitor. They would suffice for an ideal capacitor, but real world brings other, ugly metrics. Like ESR, capacity coefficient with temperature or voltage, frequency response, etc. Circuits designed around quirks of particular tech can fail if the substitute differs there. Even being too good can cause trouble, eg. high-ESR caps naturally keep peak current in check so substituting with a theoretically superior low-ESR part can cause the whole thing to blow up. Adding ESR is trivial - but that's no longer a drop-in replacement, but rather a circuit redesign. So we don't replace electrolytics with something else not because polarization is important, it's just a nuisance. We keep them because of many other parameters, less obvious than C, V and polarization.
$endgroup$
2
$begingroup$
One thing that should also be noted is that in applications where the frequency response of the capacitor is important, you can't just replace one type with another, since they work well at different frequency ranges. Examples are e.g. noise filters.
$endgroup$
– nshct
Apr 8 at 21:22
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
Apr 8 at 21:25
$begingroup$
Suggestion: add to your answer a link about ESR : avnet.com/wps/portal/abacus/resources/engineers-insight/article/…
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
$begingroup$
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Electrically speaking, non-polarized capacitor is always better than a polarized one. Yes, you can always replace with a non-polarized capacitor with exactly same rating.
But there is an assumption hidden here:Provided you can find one that's physically small enough to fit on your board and cheap enough to fit in your budget.
And the fact that you can't is the only reason we use polarized caps.
I assume that, if we ever learn to make non-polarized caps that are as cheap and dense (capacity-per-volume) as electrolytic ones, the polarized capacitors will vanish.
Side note - voltage and capacitance are not the only electrical parameters of a capacitor. They would suffice for an ideal capacitor, but real world brings other, ugly metrics. Like ESR, capacity coefficient with temperature or voltage, frequency response, etc. Circuits designed around quirks of particular tech can fail if the substitute differs there. Even being too good can cause trouble, eg. high-ESR caps naturally keep peak current in check so substituting with a theoretically superior low-ESR part can cause the whole thing to blow up. Adding ESR is trivial - but that's no longer a drop-in replacement, but rather a circuit redesign. So we don't replace electrolytics with something else not because polarization is important, it's just a nuisance. We keep them because of many other parameters, less obvious than C, V and polarization.
$endgroup$
Can I use a non-polarized capacitor with the same voltage and capacitance instead of these polarizing capacitors?
Electrically speaking, non-polarized capacitor is always better than a polarized one. Yes, you can always replace with a non-polarized capacitor with exactly same rating.
But there is an assumption hidden here:Provided you can find one that's physically small enough to fit on your board and cheap enough to fit in your budget.
And the fact that you can't is the only reason we use polarized caps.
I assume that, if we ever learn to make non-polarized caps that are as cheap and dense (capacity-per-volume) as electrolytic ones, the polarized capacitors will vanish.
Side note - voltage and capacitance are not the only electrical parameters of a capacitor. They would suffice for an ideal capacitor, but real world brings other, ugly metrics. Like ESR, capacity coefficient with temperature or voltage, frequency response, etc. Circuits designed around quirks of particular tech can fail if the substitute differs there. Even being too good can cause trouble, eg. high-ESR caps naturally keep peak current in check so substituting with a theoretically superior low-ESR part can cause the whole thing to blow up. Adding ESR is trivial - but that's no longer a drop-in replacement, but rather a circuit redesign. So we don't replace electrolytics with something else not because polarization is important, it's just a nuisance. We keep them because of many other parameters, less obvious than C, V and polarization.
edited Apr 9 at 10:03
Ismael Miguel
17319
17319
answered Apr 8 at 9:13
Agent_LAgent_L
1,095611
1,095611
2
$begingroup$
One thing that should also be noted is that in applications where the frequency response of the capacitor is important, you can't just replace one type with another, since they work well at different frequency ranges. Examples are e.g. noise filters.
$endgroup$
– nshct
Apr 8 at 21:22
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
Apr 8 at 21:25
$begingroup$
Suggestion: add to your answer a link about ESR : avnet.com/wps/portal/abacus/resources/engineers-insight/article/…
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
2
$begingroup$
One thing that should also be noted is that in applications where the frequency response of the capacitor is important, you can't just replace one type with another, since they work well at different frequency ranges. Examples are e.g. noise filters.
$endgroup$
– nshct
Apr 8 at 21:22
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
Apr 8 at 21:25
$begingroup$
Suggestion: add to your answer a link about ESR : avnet.com/wps/portal/abacus/resources/engineers-insight/article/…
$endgroup$
– Overmind
Apr 10 at 5:00
2
2
$begingroup$
One thing that should also be noted is that in applications where the frequency response of the capacitor is important, you can't just replace one type with another, since they work well at different frequency ranges. Examples are e.g. noise filters.
$endgroup$
– nshct
Apr 8 at 21:22
$begingroup$
One thing that should also be noted is that in applications where the frequency response of the capacitor is important, you can't just replace one type with another, since they work well at different frequency ranges. Examples are e.g. noise filters.
$endgroup$
– nshct
Apr 8 at 21:22
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
Apr 8 at 21:25
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
Apr 8 at 21:25
$begingroup$
Suggestion: add to your answer a link about ESR : avnet.com/wps/portal/abacus/resources/engineers-insight/article/…
$endgroup$
– Overmind
Apr 10 at 5:00
$begingroup$
Suggestion: add to your answer a link about ESR : avnet.com/wps/portal/abacus/resources/engineers-insight/article/…
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
$begingroup$
The physical size of a capacitor is a function of the thickness of the dielectric (among other things).
Early on, it was discovered that the oxides of certain metals (aluminum and tantalum in particular) made good dielectrics, and could be made very thin through a chemical process — orders of magnitude thinner than other dielectrics such as waxed/oiled paper and plastic film. Therefore, the electrolytic capacitor was invented to provide high capacitance in a reasonable volume.
Unfortunately, the chemical process requires that the voltage across the capacitor must have only a single polarity, so these capacitors are "polarized". Reversing the polarity degrades and eventually destroys the oxide layer. It's something we just have to live with in order to take advantage of this technology.
The ability to produce high-value capacitors in nonpolarized technologies such as multilayer ceramic means that it is now possible to use them where only a polarized capacitor would have been previously available. There is generally no problem with making this substitution, although you may need to consider some of the quirks of the technology you're switching to.
For example, some high-K (high dielectric constant) ceramics exhibit significant capacitance changes with voltage. This might be acceptable in a coupling or bypass application, but completely unacceptable in a filter design.
$endgroup$
1
$begingroup$
There is a specific use case where replacing tantalum devices with MLCC parts can have unfortunate effects: at the output of some (older) LDO regulators which require a certain minimum output ESR. It can be done, but some care is necessary.
$endgroup$
– Peter Smith
Apr 8 at 9:03
$begingroup$
Very nice answer! I'm trying to figure out if asking "Why does the chemical process used to make capacitor dielectrics from oxides of certain metals (aluminum and tantalum in particular) require that the voltage across the capacitor must have only a single polarity?" but I'm not confident it will be on topic. Is there any chance you could add a hint here?
$endgroup$
– uhoh
Apr 8 at 10:28
add a comment |
$begingroup$
The physical size of a capacitor is a function of the thickness of the dielectric (among other things).
Early on, it was discovered that the oxides of certain metals (aluminum and tantalum in particular) made good dielectrics, and could be made very thin through a chemical process — orders of magnitude thinner than other dielectrics such as waxed/oiled paper and plastic film. Therefore, the electrolytic capacitor was invented to provide high capacitance in a reasonable volume.
Unfortunately, the chemical process requires that the voltage across the capacitor must have only a single polarity, so these capacitors are "polarized". Reversing the polarity degrades and eventually destroys the oxide layer. It's something we just have to live with in order to take advantage of this technology.
The ability to produce high-value capacitors in nonpolarized technologies such as multilayer ceramic means that it is now possible to use them where only a polarized capacitor would have been previously available. There is generally no problem with making this substitution, although you may need to consider some of the quirks of the technology you're switching to.
For example, some high-K (high dielectric constant) ceramics exhibit significant capacitance changes with voltage. This might be acceptable in a coupling or bypass application, but completely unacceptable in a filter design.
$endgroup$
1
$begingroup$
There is a specific use case where replacing tantalum devices with MLCC parts can have unfortunate effects: at the output of some (older) LDO regulators which require a certain minimum output ESR. It can be done, but some care is necessary.
$endgroup$
– Peter Smith
Apr 8 at 9:03
$begingroup$
Very nice answer! I'm trying to figure out if asking "Why does the chemical process used to make capacitor dielectrics from oxides of certain metals (aluminum and tantalum in particular) require that the voltage across the capacitor must have only a single polarity?" but I'm not confident it will be on topic. Is there any chance you could add a hint here?
$endgroup$
– uhoh
Apr 8 at 10:28
add a comment |
$begingroup$
The physical size of a capacitor is a function of the thickness of the dielectric (among other things).
Early on, it was discovered that the oxides of certain metals (aluminum and tantalum in particular) made good dielectrics, and could be made very thin through a chemical process — orders of magnitude thinner than other dielectrics such as waxed/oiled paper and plastic film. Therefore, the electrolytic capacitor was invented to provide high capacitance in a reasonable volume.
Unfortunately, the chemical process requires that the voltage across the capacitor must have only a single polarity, so these capacitors are "polarized". Reversing the polarity degrades and eventually destroys the oxide layer. It's something we just have to live with in order to take advantage of this technology.
The ability to produce high-value capacitors in nonpolarized technologies such as multilayer ceramic means that it is now possible to use them where only a polarized capacitor would have been previously available. There is generally no problem with making this substitution, although you may need to consider some of the quirks of the technology you're switching to.
For example, some high-K (high dielectric constant) ceramics exhibit significant capacitance changes with voltage. This might be acceptable in a coupling or bypass application, but completely unacceptable in a filter design.
$endgroup$
The physical size of a capacitor is a function of the thickness of the dielectric (among other things).
Early on, it was discovered that the oxides of certain metals (aluminum and tantalum in particular) made good dielectrics, and could be made very thin through a chemical process — orders of magnitude thinner than other dielectrics such as waxed/oiled paper and plastic film. Therefore, the electrolytic capacitor was invented to provide high capacitance in a reasonable volume.
Unfortunately, the chemical process requires that the voltage across the capacitor must have only a single polarity, so these capacitors are "polarized". Reversing the polarity degrades and eventually destroys the oxide layer. It's something we just have to live with in order to take advantage of this technology.
The ability to produce high-value capacitors in nonpolarized technologies such as multilayer ceramic means that it is now possible to use them where only a polarized capacitor would have been previously available. There is generally no problem with making this substitution, although you may need to consider some of the quirks of the technology you're switching to.
For example, some high-K (high dielectric constant) ceramics exhibit significant capacitance changes with voltage. This might be acceptable in a coupling or bypass application, but completely unacceptable in a filter design.
edited Apr 8 at 0:02
answered Apr 7 at 22:01
Dave Tweed♦Dave Tweed
125k10155269
125k10155269
1
$begingroup$
There is a specific use case where replacing tantalum devices with MLCC parts can have unfortunate effects: at the output of some (older) LDO regulators which require a certain minimum output ESR. It can be done, but some care is necessary.
$endgroup$
– Peter Smith
Apr 8 at 9:03
$begingroup$
Very nice answer! I'm trying to figure out if asking "Why does the chemical process used to make capacitor dielectrics from oxides of certain metals (aluminum and tantalum in particular) require that the voltage across the capacitor must have only a single polarity?" but I'm not confident it will be on topic. Is there any chance you could add a hint here?
$endgroup$
– uhoh
Apr 8 at 10:28
add a comment |
1
$begingroup$
There is a specific use case where replacing tantalum devices with MLCC parts can have unfortunate effects: at the output of some (older) LDO regulators which require a certain minimum output ESR. It can be done, but some care is necessary.
$endgroup$
– Peter Smith
Apr 8 at 9:03
$begingroup$
Very nice answer! I'm trying to figure out if asking "Why does the chemical process used to make capacitor dielectrics from oxides of certain metals (aluminum and tantalum in particular) require that the voltage across the capacitor must have only a single polarity?" but I'm not confident it will be on topic. Is there any chance you could add a hint here?
$endgroup$
– uhoh
Apr 8 at 10:28
1
1
$begingroup$
There is a specific use case where replacing tantalum devices with MLCC parts can have unfortunate effects: at the output of some (older) LDO regulators which require a certain minimum output ESR. It can be done, but some care is necessary.
$endgroup$
– Peter Smith
Apr 8 at 9:03
$begingroup$
There is a specific use case where replacing tantalum devices with MLCC parts can have unfortunate effects: at the output of some (older) LDO regulators which require a certain minimum output ESR. It can be done, but some care is necessary.
$endgroup$
– Peter Smith
Apr 8 at 9:03
$begingroup$
Very nice answer! I'm trying to figure out if asking "Why does the chemical process used to make capacitor dielectrics from oxides of certain metals (aluminum and tantalum in particular) require that the voltage across the capacitor must have only a single polarity?" but I'm not confident it will be on topic. Is there any chance you could add a hint here?
$endgroup$
– uhoh
Apr 8 at 10:28
$begingroup$
Very nice answer! I'm trying to figure out if asking "Why does the chemical process used to make capacitor dielectrics from oxides of certain metals (aluminum and tantalum in particular) require that the voltage across the capacitor must have only a single polarity?" but I'm not confident it will be on topic. Is there any chance you could add a hint here?
$endgroup$
– uhoh
Apr 8 at 10:28
add a comment |
$begingroup$
Since you mention protection I'll add that polarized caps should not be used for reverse polarity protection. They will react on a reverse voltage very slowly (seconds or minutes), while typical sensitive components which are worth protecting will be dead within milliseconds. And once a polarized cap starts to absorb the reverse voltage, it may vent, explode or catch fire which (apart from the obvious problem with smoke and fire) can make it non-conductive again, exposing your circuit to the reverse voltage once more.
$endgroup$
$begingroup$
Good point here.
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
$begingroup$
Since you mention protection I'll add that polarized caps should not be used for reverse polarity protection. They will react on a reverse voltage very slowly (seconds or minutes), while typical sensitive components which are worth protecting will be dead within milliseconds. And once a polarized cap starts to absorb the reverse voltage, it may vent, explode or catch fire which (apart from the obvious problem with smoke and fire) can make it non-conductive again, exposing your circuit to the reverse voltage once more.
$endgroup$
$begingroup$
Good point here.
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
$begingroup$
Since you mention protection I'll add that polarized caps should not be used for reverse polarity protection. They will react on a reverse voltage very slowly (seconds or minutes), while typical sensitive components which are worth protecting will be dead within milliseconds. And once a polarized cap starts to absorb the reverse voltage, it may vent, explode or catch fire which (apart from the obvious problem with smoke and fire) can make it non-conductive again, exposing your circuit to the reverse voltage once more.
$endgroup$
Since you mention protection I'll add that polarized caps should not be used for reverse polarity protection. They will react on a reverse voltage very slowly (seconds or minutes), while typical sensitive components which are worth protecting will be dead within milliseconds. And once a polarized cap starts to absorb the reverse voltage, it may vent, explode or catch fire which (apart from the obvious problem with smoke and fire) can make it non-conductive again, exposing your circuit to the reverse voltage once more.
answered Apr 8 at 8:09
Dmitry GrigoryevDmitry Grigoryev
18.6k22878
18.6k22878
$begingroup$
Good point here.
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
$begingroup$
Good point here.
$endgroup$
– Overmind
Apr 10 at 5:00
$begingroup$
Good point here.
$endgroup$
– Overmind
Apr 10 at 5:00
$begingroup$
Good point here.
$endgroup$
– Overmind
Apr 10 at 5:00
add a comment |
Thanks for contributing an answer to Electrical Engineering Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f431310%2fwhy-do-we-use-polarized-capacitors%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
17
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
Apr 7 at 21:48
2
$begingroup$
Compare the prices of electrolytic caps with ceramic (or film) caps in the range of 10uF ~22uF (after taking bias voltage derating into consideration) and you will have one of the reasons.
$endgroup$
– Wesley Lee
Apr 7 at 21:54
$begingroup$
The very thin oxide layers, providing insulation for a certain polarity, provides a very compact energy storage module. Just view those useful electrolytic capacitors as early versions of self-assembled-nano-tech; the manufacturing process creates the very thin oxide layer: the oxide is GROWN or FORMED.
$endgroup$
– analogsystemsrf
Apr 7 at 22:01
4
$begingroup$
Is there a problem if these capacitors are replaced with non-polarized capacitors in this circuits?
-- no, there is no problem. But you may find it hard to find non-polarized capacitors of the same specification. Non-polarized capacitors are usually in the nF range and are usually rated for low voltage use (5V or less). If you want anything in the uF or mF and/or rated at tens of volts you will have to make do with polarized capacitors$endgroup$
– slebetman
Apr 8 at 5:22
4
$begingroup$
@slebetman "Non-polarized capacitors are usually rated for low voltage use (5V or less)" - the reality is actually opposite of what you say.
$endgroup$
– Dmitry Grigoryev
Apr 8 at 8:03