0.2-2uF cap with lowest ESR, concrete ESR values?
0.2-2uF cap with lowest ESR, concrete ESR values?
(OP)
Hi,
I'm looking for a capacitor between 0.2 and 2 uF with ESR as low as possible.
Electrolytic polymer capacitor's are not available for such low capacities, and I found several sources stating that ceramic's would have lower ESR.
This page: http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/...
says that polymer aluminum's have lowest ESR of electrolyts, but still are 3 times the ESR of ceramic capacitors.
And here: http://www.e-sonic.com/whatsnew/emag2004_3/emag_Pa... it is stated that ceramic chip capacitor's (MLCC's) have "ultra low esr", especially Class 1 (NP0/C0G).
That sounds good, but in practice I have difficulties finding concrete ESR values, and even more to find ESR values in the 100Hz-2kHz range, used in my application. This can drastically change...
What type of capacitor will guarantee lowest ESR and would there be any catalog with precise ESR information?
Thanks in advance!
{urijn
I'm looking for a capacitor between 0.2 and 2 uF with ESR as low as possible.
Electrolytic polymer capacitor's are not available for such low capacities, and I found several sources stating that ceramic's would have lower ESR.
This page: http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/...
says that polymer aluminum's have lowest ESR of electrolyts, but still are 3 times the ESR of ceramic capacitors.
And here: http://www.e-sonic.com/whatsnew/emag2004_3/emag_Pa... it is stated that ceramic chip capacitor's (MLCC's) have "ultra low esr", especially Class 1 (NP0/C0G).
That sounds good, but in practice I have difficulties finding concrete ESR values, and even more to find ESR values in the 100Hz-2kHz range, used in my application. This can drastically change...
What type of capacitor will guarantee lowest ESR and would there be any catalog with precise ESR information?
Thanks in advance!
{urijn





RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
http://us.sanyo.com/Electronic-Devices-Components/...
Keith Cress
kcress - http://www.flaminsystems.com
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
-size is not of importance.
-voltage rating and current handling neither, as I can use the oscillator at any amplitude.
-I'd like not to surpass 3€/piece
@itsmoked: the sanyo os-con's look interesting indeed, but I'm curious about the specs of ceramic variants...
To illustrate my application:
It is for a highly resonating audio series RLC oscillator, (with f_res = about 1200 Hz).
Logically I wont use a resistor, the R value will be the sum of the inductor's DCR and capacitor's ESR values.
-> given that w0 = 1/sqrt(LC) and Q = sqrt(L/C) / R
and R = DCR + ESR.
Apart from materials and design, I believe we can globally state that:
DCR = proportional to the inductor's cable length, so as L=N^2, roughly: DCR ~ sqrt(L)
ESR = inversely proportional to the capacity: ESR ~ 1/C
This gives: Q ~ sqrt(L/C) / (sqrt(L)+1/C)
So that I conclude that I should chose L/C as high as possible. I've found this confirmed using several LC sets of existing components.
I found a cheap choke of 5mH with DCR=45mOhm (no risk for saturation as the voltage rating is not of big importance for my application).
That's why I'd like to find a capacitor in that capacity range.
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
If size is not important, how about paralleling multiple lower-value caps to get an effectively lower ESR?
Glenn
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
I'd think paralleling caps gives the same results as taking a similar type of twice the capacity, no?
But, should I opt for MLCC's rather then polymers, concerning ESR? No concrete ESR values (preferably in the audio frequency domain) available?
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
A quick look in Kemet's range got the following possibles:
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
They even appear to be not that expensive...
ESL is still high enough indeed.
I didn't find ESR information though. Generally the dissipation factor @ 120Hz is specified.
Logically I can presume ESR = tan(d)/(2*pi*120*C), right?
Strange, when I compare ESR at 120Hz and the ESR calculated with the dissipation factor with this formula, for example in the Nichicon FPCAP catalog (http://www.nichicon.co.jp/english/products/pdf/201...), for some capacitor's it's coherent, for others I obtain a ratio of thousand...!?
I'll maybe just buy some components and measure ESR myself...
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
ESR is a catch-all measurement for capacitors that is generally used when selecting capacitors for filtering (power supply noise/ripple). Dissipation Factor is an older figure-of-merit that lumps ESR and ESL together in one number.
If your aplication was HF to UHF the best choice would be NP0 ceramics. Since your application is in the audio range, I would use a polystyrene, polypropylene, or Teflon film (very low DF). Given your cost target I would forget about Teflon.
RE: 0.2-2uF cap with lowest ESR, concrete ESR values?
But the relation of dielectric absorption to the capacitor's R is (the main part of) ESR.
Maybe you want to state that this absorption factor is more directly connected to Q as it is independent of C? But I find ESR more practical in my mathematical approaches...
Dissipation factor rather lumps ESR and wC together (http://en.wikipedia.org/wiki/Dissipation_factor).
Thanks for the audio related tip, I'll try polypropylenes soon!
For the moment I'm more concerned about the parasitic capacitance of the 5mH choke..!