At 01:12 PM 29/10/2005, nobozoz wrote:
For optimal low-frequency power bypassing performance, you want the lowest ESR from DC to about 100 kHz from your aluminum electrolytic caps. At mid-frequencies, the tantalum chip caps kick in. At high-frequencies, the ceramic chip caps take over. At the highest frequencies the power and ground-planes, feedthroughs, trace sizes and spacing take over. More than you wanted to know, eh?
More than I can understand anyway. :) Thanks for this information, though. How do I tell what capacitor has the lowest ESR at 100kHz? I assume I look at impedence @ 20C/100kHz and ripple @ 105C/100kHz, but I'm not sure what a "good" number is.
If I read the articles correctly, then I assume that the higher the mA ripple and the lower the mOhm impedence the better. I have yet to find ratings like the Rubycon below. The best I've found so far is 68mOhm and 755mA on a 1000uF 6.3V Nichicon capacitor from Mouser. Would that be sufficient, if the Rubycon is the one to go with, or should I keep looking?
T
Capacitors on motherboard, Rubycon ZA-series 1000uF 6.3V. This capacitor has max ripple current at max operation temperature (105C,100kHz) of 1650mA and impedance of 24mOhm (at 20C, 100kHz)
