Re: gEDA-user: ESR of 2.2u ceramic capacitor

[John Doty <jpd@xxxxxxxxxxxxx>]

On Feb 22, 2006, at 11:55 AM, Bill Sloman wrote:

> At 18:59 22-2-2006, you wrote:
> > Hello
> >
> > Does anyone has experience how much ESR a modern 2.2u ceramic  
> > capacitor
> > can have? Less than 200mOhm?
>
> The manufacturers might. Google is your friend
>
> http://www.low-esr.com/esrfreqperfcurves.html-ssi#NMC2R2
>
> For that particular capacitor, ESR is claimed to decrease with  
> frequency. from about 1.5R at 1kHz to about 0.01R at 100kHz.

When you see a spec like that, you should smell a rat. If it obeys  
Ohm's law, it won't depend on frequency.  If it depends on frequency,  
it will almost certainly depend on other details of the test  
procedure (which this site doesn't specify). The dissipation here is  
probably due to dielectric hysteresis, not resistance. How that  
relates to the requirements of your circuit depends on the circuit.

Ohmic resistance of ceramics is usually very small (the electrodes  
are metal), but high K ceramic dielectrics generally have a lot of  
hysteresis, which can be trouble in some applications.

John Doty              Noqsi Aerospace, Ltd.
jpd@xxxxxxxxxxxxx