what is esr of a capacitor

[nikhilele]

esr of capacitor

I have electrolytic capacitor what can be esr of those.

i need a 2200uF capacitor at output of my Dc/Dc convertor then which type of capacitor should I use.

When i insert electrolytic capacitor the voltage at ouput fluctuates.

 

[Miguel Gaspar]

what is esr capacitor

ESR Equivalente Series Resistor

Refers toa model of a real capacitor, wich includes a serial resistor.

For that value 2200uF you don't have options

 

[vicky]

capacitor failure modes that raise the esr

HI DEAR


ESR Defined
ESR is the sum of in-phase AC resistance. It includes resistance of the dielectric, plate material, electrolytic solution, and terminal leads at a particular frequency. ESR acts like a resistor in series with a capacitor (thus the name Equivalent Series Resistance). This resister can cause circuits to fail that look just fine on paper and is often the failure mode of capacitors.
To charge the dielectric material current needs to flow down the leads, through the lead plate junction, through the plates themselves - and even through the dielectric material. The dielectric losses can be thought of as friction of aligning dipoles and thus appear as an increase (or a reduction of the rate of decrease -- this increase is what makes the resistance vs freq line to go flat.) of measured ESR as frequency increases.
As the dielectric thickness increases so does the ESR. As the plate area increases, the ESR will go down if the plate thickness remains the same.
To test a Capacitors ESR (see the Cap Wizard) requires something other than a standard capacitor meter. While a capacitor value meter is a handy device, it will not detect capacitor failure modes that raise the ESR. As the years go by, more and more designs rely on low ESR capacitors to function properly. ESR failed caps can present circuit symptoms that are difficult to diagnose.

 

[nikhilele]

esr value capacitor parallel ceramic electrolytic

Refers toa model of a real capacitor, wich includes a serial resistor.

For that value 2200uF you don't have options

Cannot we connect capacitors in parallel and have a good esr value

 

[IanP]

esr value capacitor parallel ceramic electrolytic

Connecting caps in parallel may be not ideal but is a good idea ..
If you compare 1000µF and 2000µF you will find out that connecting two 1000µF caps in parallel will be better "equivalent" to one 2000µF .. see table below .. both of the same family ..
However, it is not a good idea if you try to replace one 2000µF low-ESR cap with two (or more) standard caps ..

If you really need a low-ESR caps you have to select proper type and value ..
Keep in mind that Ripple voltage = Current X ESR


Regards,
IanP

 

[easternbean]

if you want low esr ,i dont suggest electrolytic capacitors , i prefer ceremic capacitor or taltium capaciotr , but they are more expensive!:-(

 

[nikhilele]

for high it is very very hard to find tantalum and neraly impossible to find ceramic capacitor so we donot have other choice except electrolytic.

 

[ptmsl]

For switching supplies better use Low ESR and long life capacitors. Most manufacturers have a low ESR series. Depending on your frequency you might want to consider ESL (Equivalent series inductance) as well or use high frequency ceramics or polypropylene caps in parallel with the bulk capacitor.

 

[nikhilele]

Depending on your frequency you might want to consider ESL (Equivalent series inductance) as well or use high frequency ceramics or polypropylene caps in parallel with the [b][color=blue]bulk capacitor[/color][/b]

this bulk capacitor is of Electrolytic type ok.

 

[mohammad mokhtar]

Dear friend
as every one has said esr is the abbreviation of effective series resistance of a capacitor , easily bwhen the dilectric of th elyctrolytic capacitor ( the insulation medium ) is exposed to electric field there will be a heat generated in that dilectric to analyze this losses we simulate it by a small series resistance, the losses in that resistance is equal to the losses in the dilectric medium. For your application you have to choose a high quality electrolytic capacitor with loow esr and ripple current that fits your switching frequency ( ripple current, esr, and temperature Are the parameters that control your design).
Regards