I'm currently working on a project where I'm designing a DC-DC converter circuit. I'm trying to make the most efficient design possible, and I've recently started to explore capacitors and their respective ESR.
I was curious. It seems that the ESR is inversely proportional to the capacitance rating e.g. a 470 uF cap has a lower ESR than that of a 22 uF of the same chemistry. I guess this is due to the function of 1/sC (in part, among other things). So in terms of actually selecting a capacitor, why not select the largest possible?
I need a minimum capacitor value of 22 uF for my input and coupling (I'm using a SEPIC topology), but I'm trying to decide why I shouldn't just go with a larger capacitor that has a lower ESR. The capacitors aren't that expensive, so it's not really a problem for me to buy larger ones. Nor is the size of the board a problem. Overall, I'm looking for efficiency.
That said, is it just better for me to buy the largest capacitors with the lowest ESRs possible?
On a side note, would you recommend that I use many smaller electrolytics in parallel, or should I try to get away with a single large capacitor?
Thanks,
Obby
I was curious. It seems that the ESR is inversely proportional to the capacitance rating e.g. a 470 uF cap has a lower ESR than that of a 22 uF of the same chemistry. I guess this is due to the function of 1/sC (in part, among other things). So in terms of actually selecting a capacitor, why not select the largest possible?
I need a minimum capacitor value of 22 uF for my input and coupling (I'm using a SEPIC topology), but I'm trying to decide why I shouldn't just go with a larger capacitor that has a lower ESR. The capacitors aren't that expensive, so it's not really a problem for me to buy larger ones. Nor is the size of the board a problem. Overall, I'm looking for efficiency.
That said, is it just better for me to buy the largest capacitors with the lowest ESRs possible?
On a side note, would you recommend that I use many smaller electrolytics in parallel, or should I try to get away with a single large capacitor?
Thanks,
Obby