Why do we use polarized capacitors?Are tantalum capacitors safe for use in new designs?Why does the LM1117...
Does bootstrapped regression allow for inference?
I’m planning on buying a laser printer but concerned about the life cycle of toner in the machine
What causes the sudden spool-up sound from an F-16 when enabling afterburner?
Why doesn't a const reference extend the life of a temporary object passed via a function?
extract characters between two commas?
Does the average primeness of natural numbers tend to zero?
What happens when a metallic dragon and a chromatic dragon mate?
How to answer pointed "are you quitting" questioning when I don't want them to suspect
How to manage monthly salary
Finding files for which a command fails
Calculate Levenshtein distance between two strings in Python
Extreme, but not acceptable situation and I can't start the work tomorrow morning
Doomsday-clock for my fantasy planet
How to make payment on the internet without leaving a money trail?
Is "plugging out" electronic devices an American expression?
COUNT(*) or MAX(id) - which is faster?
What does "enim et" mean?
Why was the "bread communication" in the arena of Catching Fire left out in the movie?
What do you call something that goes against the spirit of the law, but is legal when interpreting the law to the letter?
Prime joint compound before latex paint?
Does a dangling wire really electrocute me if I'm standing in water?
Why did the Germans forbid the possession of pet pigeons in Rostov-on-Don in 1941?
Hosting Wordpress in a EC2 Load Balanced Instance
Manga about a female worker who got dragged into another world together with this high school girl and she was just told she's not needed anymore
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
New contributor
$endgroup$
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
New contributor
$endgroup$
12
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
yesterday
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
yesterday
$begingroup$
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
yesterday
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
21 hours ago
3
$begingroup$
@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
18 hours ago
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
New contributor
$endgroup$
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
New contributor
New contributor
edited 7 hours ago
JakeGould
1155
1155
New contributor
asked yesterday
hamid mousavihamid mousavi
966
966
New contributor
New contributor
12
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
yesterday
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
yesterday
$begingroup$
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
yesterday
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
21 hours ago
3
$begingroup$
@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
18 hours ago
add a comment |
12
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
yesterday
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
yesterday
$begingroup$
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
yesterday
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
21 hours ago
3
$begingroup$
@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
18 hours ago
12
12
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
yesterday
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
yesterday
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
yesterday
$begingroup$
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
yesterday
$begingroup$
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
yesterday
$begingroup$
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
yesterday
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
21 hours ago
$begingroup$
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
21 hours ago
3
3
$begingroup$
@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
18 hours ago
$begingroup$
@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
18 hours ago
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 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. Circuit designed around quirks of particular tech can fail if 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.
$endgroup$
$begingroup$
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
5 hours ago
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
5 hours ago
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
17 hours ago
$begingroup$
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
15 hours ago
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.
$endgroup$
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["\$", "\$"]]);
});
});
}, "mathjax-editing");
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
});
}
});
hamid mousavi is a new contributor. Be nice, and check out our Code of Conduct.
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 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. Circuit designed around quirks of particular tech can fail if 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.
$endgroup$
$begingroup$
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
5 hours ago
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
5 hours ago
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 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. Circuit designed around quirks of particular tech can fail if 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.
$endgroup$
$begingroup$
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
5 hours ago
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
5 hours ago
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 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. Circuit designed around quirks of particular tech can fail if 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 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. Circuit designed around quirks of particular tech can fail if 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 4 hours ago
answered 17 hours ago
Agent_LAgent_L
1,025611
1,025611
$begingroup$
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
5 hours ago
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
5 hours ago
add a comment |
$begingroup$
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
5 hours ago
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
5 hours ago
$begingroup$
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
5 hours ago
$begingroup$
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
5 hours ago
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
5 hours ago
$begingroup$
@nshct that's what I've meant by "other, ugly metrics" : ) Edited
$endgroup$
– Agent_L
5 hours ago
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
17 hours ago
$begingroup$
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
15 hours ago
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
17 hours ago
$begingroup$
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
15 hours ago
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 yesterday
answered yesterday
Dave Tweed♦Dave Tweed
123k10153267
123k10153267
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
17 hours ago
$begingroup$
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
15 hours ago
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
17 hours ago
$begingroup$
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
15 hours ago
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
17 hours ago
$begingroup$
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
17 hours ago
$begingroup$
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
15 hours ago
$begingroup$
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
15 hours ago
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.
$endgroup$
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.
$endgroup$
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 18 hours ago
Dmitry GrigoryevDmitry Grigoryev
18.3k22777
18.3k22777
add a comment |
add a comment |
hamid mousavi is a new contributor. Be nice, and check out our Code of Conduct.
hamid mousavi is a new contributor. Be nice, and check out our Code of Conduct.
hamid mousavi is a new contributor. Be nice, and check out our Code of Conduct.
hamid mousavi is a new contributor. Be nice, and check out our Code of Conduct.
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
12
$begingroup$
It's not because we want them polarized, but them being polarized is a consequence of how they'r emade.
$endgroup$
– Hearth
yesterday
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
yesterday
$begingroup$
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
yesterday
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
21 hours ago
3
$begingroup$
@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
18 hours ago