What if you put a solid poly in parallel with a lytic?

[PCBONEZ]

My thinking is the poly would take most of the ripple due to the lower ESR but the lytic could still provide the bulk capacitance.

Does that make sense?

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[kc8adu]

Re: What if you put a solid poly in parallel with a lytic?

yes.thats what will happen.a lytic will also do a bit better cleaning up low freq noise/ripple.
move to a more apropriate forum.

[i4004]

Re: What if you put a solid poly in parallel with a lytic?

do we here have an idea for extra durable mod?
although putting 2caps in lace of one doesn't need to be easiest thing to do.

i was putting(pairing) one cap on top of another(top to top. so to say) when i didn't have cap of proper value, and then pull the wires from top one to bottom one.
esr measurements proved that esr went down, just like one would expect with parallel resistors.

[PCBONEZ]

Re: What if you put a solid poly in parallel with a lytic?

Thought about something like that before.

Also might help where you have long rows of small diameter caps and you can't find small diameter replacements in low enough esr.

[kc8adu]

Re: What if you put a solid poly in parallel with a lytic?

lead length could be an issue though in a vrm.

[PCBONEZ]

Re: What if you put a solid poly in parallel with a lytic?

I thought of that.
I would put poly (whichever cap has lower ESR) on the leads which should help compensate for wire length.

I found the right caps for the project that brought this up anyway now but the question remained on my mind so I asked for future reference.

About previous comment:
What puzzles me is how with two caps in parallel one would be better at cleaning up low freq and the other better at high freq.
- What you said makes sense to me but it's contrary to what they teach about caps in parallel and frequency response. When two caps in parallel aren't the same caps that 'rule' goes *poof* and the math gets real nasty.

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