Least ESR value available in Electrolytic Capacitor

[iamakda]

What is the least value of ESR available in electrolytic capacitor? It would be great if the value of capacitance is anything from 50uF to 200uF and 100V. I have found this:

http://uk.farnell.com/jsp/search/pro...ote-1547013-pr

but is there anything else available in your knowledge?

Thank you very much.

[tom66]

Re: Least ESR value available in Electrolytic Capacitor

Around 5 to 10 milliohm.

At that point the resistance of the capacitor leads becomes significant, and it works out better to use many smaller caps in parallel.

[iamakda]

Re: Least ESR value available in Electrolytic Capacitor

Around 5 to 10 milliohm.

At that point the resistance of the capacitor leads becomes significant, and it works out better to use many smaller caps in parallel.

Hi Tom,

Could you please give me the link of this capacitor? I will be really grateful.

[tom66]

Re: Least ESR value available in Electrolytic Capacitor

You just found one with 8.5 mohm, you're not going to get much further.

You can get 6.5mohm at 1800uF, 16V:
https://cdn.badcaps-static.com/pdfs/...43c4079d93.pdf
but that's not 100V.

[iamakda]

Re: Least ESR value available in Electrolytic Capacitor

You just found one with 8.5 mohm, you're not going to get much further.

You can get 6.5mohm at 1800uF, 16V:
https://cdn.badcaps-static.com/pdfs/...43c4079d93.pdf
but that's not 100V.

Ok...do you know something for 100V ?

[mariushm]

Re: Least ESR value available in Electrolytic Capacitor

There's no such thing as least esr available.

Capacitors are made for various purposes, some are more low esr than others, while some are higher esr but designed to be used for other purposes where esr doesn't matter that much.

That series of capacitors you link to, ZLH, is a low esr series of capacitors and works for SOME cases, depending where the capacitors are used on a device and what specifications the old capacitors had.

It is however not one of lowest esr possible type capacitors, which means it may not be suitable for example to be used on a motherboard near the processor. For that you need very low esr capacitors.

You can check the datasheets of various capacitors, and look up the Impedance at 100kHz column. ESR is a different concept, but at 100kHz the Impedance value is usually very close to the ESR value of an capacitor so for our purposes they might as well be the same thing.

ps. lots of posts between the time i saw the initial post and my reply, i opened the comment in browser and went to lunch...

Anyway, you ask for something for 100v.

100v is kind of a very high voltage.

I have to ask what the capacitor is used for. ESR is not that relevant for some uses of capacitors, such as when the capacitor is used in a linear power supply, or an audio amplifier to filter the voltage coming from the transformer... these don't work at high frequencies.
For an audio amplifier, you're better off selecting capacitors based on where they're used... if they're in audio signal path, maybe you're better off with film capacitors for example.

[tom66]

Re: Least ESR value available in Electrolytic Capacitor

I'm designing some automotive components presently, and the real killer in my application is that at the minimum operating temperature of around -40°C, ESR goes through the roof, causing havoc with little switching supplies on my boards. I'm having to use tantalums for most stuff.

[iamakda]

Re: Least ESR value available in Electrolytic Capacitor

I'm designing some automotive components presently, and the real killer in my application is that at the minimum operating temperature of around -40°C, ESR goes through the roof, causing havoc with little switching supplies on my boards. I'm having to use tantalums for most stuff.

how the ESR is related to temperature? what is the relation? they are inversely proportional or directly proportional?

[tom66]

Re: Least ESR value available in Electrolytic Capacitor

how the ESR is related to temperature? what is the relation? they are inversely proportional or directly proportional?

Typically ESR is 5x to 20x higher at -40°C than 25°C. So your 8.5 mohm capacitor becomes as much as 170 mohm. Further below -40°C the capacitor's electrolyte freezes and ESR becomes irrelevant: the device is no longer a capacitor. Fortunately the capacitors can be warmed up by self-heating caused by ripple current, which will cause their ESR to fall.

[iamakda]

Re: Least ESR value available in Electrolytic Capacitor

Typically ESR is 5x to 20x higher at -40°C than 25°C. So your 8.5 mohm capacitor becomes as much as 170 mohm. Further below -40°C the capacitor's electrolyte freezes and ESR becomes irrelevant: the device is no longer a capacitor. Fortunately the capacitors can be warmed up by self-heating caused by ripple current, which will cause their ESR to fall.

ok...thanks for the information....

[budm]

Re: Least ESR value available in Electrolytic Capacitor

You can learn more here:
http://www.edn.com/design/components...r-temperatures

https://www.badcaps.net/forum/showthread.php?t=26140