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ESR of SEPIC capacitor

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eem2am

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Hello,

i am using this ceramic capacitor (2u2 1210, 100V, ceramic)

C1210C225M1RACTU

do you know what is its ESR?...

Its in a 140KHz, 36V to 5V SEPIC (@ 2.5W )as the SEPIC capacitor.
It has a maximum RMS current of 222mA in it.

Cap datasheet:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/vapubfiles/F3102_X7R.pdf/$file/F3102_X7R.pdf
 

Hello,

i am using this ceramic capacitor (2u2 1210, 100V, ceramic)

C1210C225M1RACTU

do you know what is its ESR?...

Its in a 140KHz, 36V to 5V SEPIC (@ 2.5W )as the SEPIC capacitor.
It has a maximum RMS current of 222mA in it.

Cap datasheet:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/vapubfiles/F3102_X7R.pdf/$file/F3102_X7R.pdf

If the data sheet does not tell you then you need another data sheet or a manufacturer who will give you this information, if it is important to you and your application.

Ideally they will present a plot of impedance versus frequency curves for a range of values within a particular family and for ceramics those curves will demonstrate the capacitance, the ESR (Equivalent Series Resistance) and the ESL (Equivalent Series Inductance)..

As an example I just made up..



The device is effectively a series LCR circuit and at the LC resonant frequency you will get minimum impedance as limited by the ESR. In this case with 1A driving 10mR that is 10mV or 40dB down.

Below the device resonant frequency it behaves as a capacitor. Above it it behaves as an inductor.

Genome
 
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    eem2am

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In estimate, this esr is between 10mohm and 30mohm.
 
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    eem2am

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Thankyou

leo_o2....

i appreciate your estimation of 0.03 Ohms.

.....but that would mean that with a ripple current of 2A RMS.....this 1210 capacitor would dissipate just 120mW? (by I^2.R)..........

...it seems unbelievable that a mere, tiny 1210 capacitor could handle a whopping great 2 Amps of ripple current.

am i right?
 

The Murata tool e.g. calculates nearly 4 Arms allowed current at 140 kHz for a similar capacitor, assuming 20K temperature rise.
 
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    eem2am

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If the load is 2A, it doesn't mean 2A charging/discharging current always.
 

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