Specs of electrolytic capacitors - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 19, 2021, 06:51:13 pm
content: Hi,The 687KXM025M (680uF , 25v) electrolytic capacitor is far better than the UPS1E681MPD (680uF , 25v) electrolytic capacitor.It has a lifetime of 4000 hrs vs 2000 hrs, its ripple current rating (at 100khz) is 1.8A vs 1A.Yet its price is £0.09 @ 8k vs £0.15 @ 5k.It costs 50% less!!!By rights , nobody should be using the UPS1E681MPD. Why are they?Are the specs not always to be trusted or something?687KXM025M (680uF , 25v) Electrolytic capacitorhttps://www.illinoiscapacitor.com/pdf/seriesDocuments/KXM%20series.pdfUPS1E681MPD (680uF , 25v) Electrolytic capacitorhttps://www.nichicon.co.jp/english/products/pdfs/e-ups.pdf

author: TimFox
author_rank: Super Contributor
timestamp: June 19, 2021, 07:53:25 pm
content: Are you comparing the prices at two different quantities (8k and 5k), or was that a typo?

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: June 19, 2021, 09:55:06 pm
content: Besides the difference in order quantity to have that price do mind that they have different purposes specified in their datasheets (one gp. the other for switching supplies).Also the one from Nichicon has to make a long travel from Japan and somedays the earth rotation is in the wrong way.pps: say Hi to Treez, I liked that handle a bit more than this one.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 19, 2021, 10:01:10 pm
content: ESR is different by ~4x.IC is American (CoO who knows?), maybe not as available in certain markets. Or just different availability. IC wasn't stocked at DK until relatively recently (some years back) but they've been around a long time otherwise (I recall first seeing them at Allied).Cost still doesn't really mean much. Try quoting more like 100k of each, from various suppliers or in various locations on the planet, and see what it is then?Tim

author: Faringdon
author_rank: Super Contributor
timestamp: June 19, 2021, 10:34:18 pm
content: Hi, Please may i put forward this similar question?...*******************************************************************************We have a 3V3 rail that supplies only 20mA.But we want some bulk capacitance on it. Elsewhere on the same board we are already using several 100uF , 25V Al Electrolytic capacitors. Therefore , we elect to simply use one of these on the 3V3 rail to provide bulk capacitance.We have two 100Uf, 25V Al Electrolytic capacitors to choose from….1).. 25ZL100MEFCT16.3X11Or..2).. 25YXJ100MTA5X11..We want to choose the one that will last the longest, say if the customer uses the equipment in a hot environment…we want to choose the capacitor that will take longer to dry out.But which one will avoid drying out for the longer time?25ZL100MEFCT16.3X11 is said to be rated for 0.4A ripple at 100khz and rated for 2000 hrs at 105degC, whereas 25YXJ100MTA5X11 is rated for 0.25A ripple at 100khz, but rated for 7000 hrs at 105degC.……do you agree that its impossible to know which capacitor will last longest?, since there quoted ripple currents are different…in other words, the 25YXJ100MTA5X11 is said to last for the longer time, but this is when running at only half the ripple current as the 25ZL100MEFCT16.3X11*******************************************************************************

author: The Soulman
author_rank: Super Contributor
timestamp: June 20, 2021, 08:46:19 am
content: How much ripple current do you expect on your 3,3 Volt "20mA" rail??

author: Faringdon
author_rank: Super Contributor
timestamp: June 20, 2021, 10:26:37 am
content: QuoteVirtually none........its fed by a linear reg from 5V....and its only get a few micros on it.Also, what do you think about running a 25V electrolytic on a 3V3 rail.........i had heard that an Al El cap needs at least 10% of its rated voltage on it before it "forms" properly.......3v3 isnt far off 10% of 25v.......maybe the "100uf" Al El cap wont be anywhere near 100uF?**************************************************Please may i ask another related question here?...as i know its bad to start multiple threads on the same theme......The below article states that a 10degC reduction in ambient temperature for a Aluminium polymer capacitor results in a ten-fold increase in lifetime. Is this true?....I have heard Arrhenius' Law....but never this "ten-fold" law.https://www.rs-online.com/designspark/aluminum-electrolytic-vs-aluminum-polymer-capacitor-and-how-its-benefits-are-used-properly**************************************************

author: SeanB
author_rank: Super Contributor
timestamp: June 20, 2021, 10:44:15 am
content: Use the longer life one, the ripple current rating will only add a small amount of extra heat if you run at full rated current, but the longer life one will last longer, if it runs around the same temperature, and with a current well under the max rated ripple. Derate for lower operation temperature and the 5000 hours extra will be well ahead of the other, as each 10C drop in operation temperature will offer more than double the rated life of the other, and thus if they run at a typical 75C the first will last 16000 hours, say 2 years, while the other will last 56000 hours, roughly 7 years, and this will increase for every lowering of operation temperature, say by not having a hot regulator cooking the capacitor, and having some airflow across the board.As to voltage a modern capacitor is fine with lower voltage, your 25V capacitor will be fine with 3V3 applied, and will last just as long. modern branded capacitors with quality pure aluminium foils do not degrade as badly as no name unknown impurity foil types, or very old ones with very old foil, made before QC got to the point they could remove down to the PPM level in the manufacturing.

author: Faringdon
author_rank: Super Contributor
timestamp: June 20, 2021, 10:56:46 am
content: QuoteThanks, i compared them on findchips.com.I believe that this is the best way in the world to compare the prices of two electronic components?.....687KXM025Mhttps://www.findchips.com/search/687KXM025MUPS1E681MPDhttps://www.findchips.com/search/UPS1E681MPD

author: Siwastaja
author_rank: Super Contributor
timestamp: June 20, 2021, 11:35:47 am
content: Free market is funny. Price doesn't always reflect quality or suitability for a specific task. It's well possible a certain part is better for your application. It's even possible a cheaper part to be better in every regard!Look at specs and the reputability of the manufacturer. If OK, cheap price isn't a problem, quite the opposite.You are indeed right that it's hard to see which part is better if one has lower ripple current rating but longer lifetime rating at that ripple current rating.Derating is the key to success. Derate voltage by 30-40%, derate ripple current by 50%, derate ambient temperature by 30-40 degC and you have a very long-life cap. I.e., a 25V 1.0A 105degC cap becomes a 16V, 0.5A, 70 degC part that lasts for many tens if not hundreds of thousands of hours.

author: Faringdon
author_rank: Super Contributor
timestamp: June 20, 2021, 03:21:58 pm
content: Thanks, please also assist with dispelling/confirming these myths about capacitors....(its a slightly new question but better than starting multiple new threads)**********************************************************************Myth 1: Wet Al Elec caps suffer damage due to high keakage current due to storage for >2 years at <40degC...This is not true, the leakage current is too low to cause damage, and reduces after 30 mins or so of having voltage appliedMyth 2: Wet Al elec caps are far more prone to damage than other cap types if stored for > 2 years at >40degc..this is trueMyth 3: You can always be sure that any batch of Wet Al elec caps that you order has been stored for <2 years at <40degC..This is not true. Any batch of wet Al elec caps may have been stored for >2 years at >40degc but distributors may try and disguise them as being fresh....since caps are cheap and not cost effective when stored in expensive temperature controlled environments. Also, electronics co's dont test caps for "state of health" before fitting them to PCBs.A Wet Al elec cap thats been stored for >2 years at >40degc is likely to have a lifetime far shorter than datasheet states.Myth 4: Tantalum caps are more prone to damage (than any other sold dielectric cap) due to high surge currents.This is not true, they just tend to have higher surge currents when a voltage is suddenly applied since they tend to have higher capacitance in smaller case sizes.Myth 5: Al elec caps suffer less wearout if operated significantly below rated voltage..this is not true, this is only true for film capsMyth 6: Film caps can better withstand surge currents than wet Al Elec caps...This is not true. We t Al Elec caps are the kings of surge current withstandMyth 7: Wet Al Elec caps suffer dry out of their dielectric even when not loaded..This is true, due to them being imperfectly sealed.Myth 8: Small thin wet Al elec caps suffer worse dielectric dryout than taller/thicker wet Al elec caps..This is trueMyth 9: A 10uf,0805,x7r,16V capacitor is more prone to cracking damage due to physical abuse than a 4.7uf,0805,x7r,16V capacitor...This is trueMyth 10: If a Solid polymer Al elec cap is run at 10degC less, then its lifetime increases by 10 times...This is not true, its 2 times.Myth 11: MLCC caps of size 1206 and greater are far more likely to suffer stress cracks than MLCC caps of size 0805 and less..this is true**********************************************************************************

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2021, 06:38:57 pm
content: Well that's an impressive list of gross over-generalisations you have there, treez.

author: Faringdon
author_rank: Super Contributor
timestamp: June 20, 2021, 06:50:35 pm
content: I think "Myth 3" is the one thats shocking...and "Myth 7"Also, "Myth 4" is definetly nonsense.

author: mariush
author_rank: Super Contributor
timestamp: June 20, 2021, 08:30:05 pm
content: Quote from: Faringdon on June 20, 2021, 10:56:46 amFindchips is a good start, but it doesn't contain all distributors of electronic components.For example I'm not sure TME.EU is listed there, they have the PS capacitor but not in stock .. $0.22 at 400pcs , $0.20 at 1600 pcs :https://www.tme.eu/en/details/ups1e681mpd/tht-low-imped-electrolytic-capacitors/nichicon/

author: mariush
author_rank: Super Contributor
timestamp: June 20, 2021, 08:37:01 pm
content: Quote from: Faringdon on June 20, 2021, 03:21:58 pmFor regular electrolytic capacitors, it's acceptable to estimate double the number of hours for every 10c decrease from the maximum temperature rating .. ex a 2000h at 105c will be 4k at 95, 8k at 85, 16k at 75c etcFor solid polymer capacitors (no electrolyte), formula is different.Fromhttps://www.illinoiscapacitor.com/tech-center/life-calculators.aspx