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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






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18












$begingroup$


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:




  1. BISS001 datasheet

  2. HC-SR501 PIR MOTION DETECTOR datasheet


  3. 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?










share|improve this question









New contributor




hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$








  • 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


















18












$begingroup$


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:




  1. BISS001 datasheet

  2. HC-SR501 PIR MOTION DETECTOR datasheet


  3. 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?










share|improve this question









New contributor




hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$








  • 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














18












18








18


2



$begingroup$


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:




  1. BISS001 datasheet

  2. HC-SR501 PIR MOTION DETECTOR datasheet


  3. 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?










share|improve this question









New contributor




hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




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:




  1. BISS001 datasheet

  2. HC-SR501 PIR MOTION DETECTOR datasheet


  3. 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






share|improve this question









New contributor




hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question








edited 7 hours ago









JakeGould

1155




1155






New contributor




hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked yesterday









hamid mousavihamid mousavi

966




966




New contributor




hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






hamid mousavi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.








  • 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




    $begingroup$
    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










3 Answers
3






active

oldest

votes


















11












$begingroup$


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.






share|improve this answer











$endgroup$













  • $begingroup$
    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





















35












$begingroup$

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.






share|improve this answer











$endgroup$









  • 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





















4












$begingroup$

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.






share|improve this answer









$endgroup$














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    3 Answers
    3






    active

    oldest

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    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    11












    $begingroup$


    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.






    share|improve this answer











    $endgroup$













    • $begingroup$
      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


















    11












    $begingroup$


    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.






    share|improve this answer











    $endgroup$













    • $begingroup$
      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
















    11












    11








    11





    $begingroup$


    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.






    share|improve this answer











    $endgroup$




    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.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    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




















    • $begingroup$
      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















    35












    $begingroup$

    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.






    share|improve this answer











    $endgroup$









    • 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


















    35












    $begingroup$

    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.






    share|improve this answer











    $endgroup$









    • 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
















    35












    35








    35





    $begingroup$

    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.






    share|improve this answer











    $endgroup$



    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.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited yesterday

























    answered yesterday









    Dave TweedDave 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
















    • 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













    4












    $begingroup$

    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.






    share|improve this answer









    $endgroup$


















      4












      $begingroup$

      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.






      share|improve this answer









      $endgroup$
















        4












        4








        4





        $begingroup$

        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.






        share|improve this answer









        $endgroup$



        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.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 18 hours ago









        Dmitry GrigoryevDmitry Grigoryev

        18.3k22777




        18.3k22777






















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