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

[Karel Kulhavy <clock@xxxxxxxxxxxxx>]

On Wed, Feb 22, 2006 at 02:20:42PM -0700, John Doty wrote:
> 
> 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.

What does it mean? That the capacitor loses capacity when switching
between charge and discharge? Like riding a snowboard with loose boots
and switching edges?

CL<
> 
> John Doty              Noqsi Aerospace, Ltd.
> jpd@xxxxxxxxxxxxx
>