[SOLVED] difference between ceramic and electrolytic capacitors?

[shaswat]

What are the difference between the electrolytic capacitors and ceramic capacitors?
As far as I know both are used for decoupling the capacitors. So how to differentiate betwen these TWINS during the desingning of power supply.

On web, I find there is the difference of range of them. Ceramic have high capacitance in small size.
is this is the only answer. Plz suggest some points that should keep in mind before using these TWINS.

 

[pradeep.g.belchada]

ceramic dont have a high capacitance, electrolytic is having high capacitance

 

[betwixt]

Electrolytics are usually the ones wih high capacitance in small size!

Electrolytic:
Better size/capacitance.
Normally polarized (have + and - ends)
Normally lower maximum working voltage, usually below 500V max.
Tend to be slighly inductive so their performance is poor at high frequencies.
Not available in very small values.
Degrade in value over time.

Ceramic:
Normally not polarized. ('super caps' are an exception)
Poor size/capacitance in larger values
Can be made to withstand very high voltages
Degrade much slower than electrolytics
Good high frequency performance.
Can be made in very small values (for example < 1pF for RF work)

For the most part, it's the high frequency performance that matters, as the frequency increases, electrolytics become less useful but ceramics work better so you often find them in parallel to use the advantages of both.

Brian.

 

[Venkadesh_M]

The main difference is electrolytic is unipolar device and ceramic is bipolar device.....

in high voltage ac small capacitance applications use ceramic and

dc biased high capacitance applications use electrolytic....

 

[shaswat]

What are the ranges (value) available for them. As you said electrolytic are not available in very small size and ceramic is available in small size. So what is the limiting range of that capacitors?

Is tantalum capacitors are same as electrolytic capacitors?

 

[tpetar]

Types of capacitor
https://en.wikipedia.org/wiki/Types_of_capacitor

https://www.radio-electronics.com/info/data/capacitor/capacitor_types.php


Best regards,
Peter

 

[godfreyl]

Common values:
Ceramic - 100pF to 100nF
Electrolytic - 10uF to 10000uF
(but you can get higher and lower values too)

Tantalum capacitors are also polarised.

If you need high quality, then plastic film caps (e.g. mylar, polystyrene or polypropylene) are better than ceramic, electrolytic or tantalum.

If you look at the website for an online store like RS-online, you can get a good idea of what's available and how much it costs.

 

[pinout]

Other important parameters are the ESR (Equivalent Series Resistance) and inductance of the capacitance structure and leads.
ESR has the biggest issue in power supplies, particularly switching supplies.
Lead and self inductance impact on any higher frequency design.
These all cause limitations in decoupling performance versus frequency, so you will often find an electrolytic in parallel with one or more ceramics.

So for audio an electrolytic is used alone or with a 100nF ceramic in parallel.

As you go up in frequency or fast digital edges it is often a 100nF (or 10nf) in parallel with 1nf (or lower) to get good high frequency decoupling.

As well as the component selection the component style and track layout also have a huge impact.
The best is a surface mount chip near the supply pin and going direct to an erarth plane.