capacitors  - Page 1
Forum section: electronics / projects

author: nus
author_rank: Contributor
timestamp: August 24, 2018, 06:00:43 pm
content: 598-AVE106M16B12T-Fhttps://au.mouser.com/ProductDetail/Cornell-Dubilier-CDE/AVE106M16B12T-F?qs=%2fha2pyFaduhFyZa2oKyKZhNPpq%2fkHI%252bZ1dVpCnoadEHf2qDQaWy4so1N7P5xKGfY647-UWX1C100MCL2https://au.mouser.com/ProductDetail/Nichicon/UWX1C100MCL2GB?qs=%2fha2pyFadugJ4a9hxfyd2SeAhIbJxOhr5VcQod%252bQ3SA%2f8pjsxCvR8g%3d%3ddoing a build the BOM has these 2 caps the only difference i can see is ripple current. don't understand why there are 2 different types of the same value. or is this ripple current fairly important

author: Gyro
author_rank: Super Contributor
timestamp: August 24, 2018, 06:43:46 pm
content: QuoteWell that one rather depends on your application. Without working through all the datasheet parameters in detail, the major difference that you are missing is that one is made by Cornell Dubilier and the other by Nichicon. They are competing parts and manufacturers like second sources.

author: coppercone2
author_rank: Super Contributor
timestamp: August 24, 2018, 06:57:57 pm
content: How do they design capacitors that have higher ripple current ratings?yea its 3 vs 4 mm.What parameter is changed? Thicker metal deposition on the film? Thicker film would imply higher voltage, but the voltage rating is the same. What results in the size difference?

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2018, 08:00:09 pm
content: The ripple current rating depends on maximum operating temperature, surface area for heat dissipation, and equivalent series resistance.

author: coppercone2
author_rank: Super Contributor
timestamp: August 24, 2018, 08:07:16 pm
content: So if they increase the amount of film and increase the film thickness it would result in a higher ripple current rating (more surface area), but wont that also increase voltage rating (if you balance it for the same capacitance, since physical seperation must be greater)? How comes it does not go up on the rating?Or is the spec just loose enough that the increased ripple current rating still leaves it in the 16V categorizer on the website? I assume if you made a 20V capacitor no one would find it, they would look for a 25V.THe direction of proportions is confusing me. It clearly has to do with physical size because they used a larger can by 1mm. Otherwise I figure maybe they could find a more thermally conductive electrolyte?

author: David Hess
author_rank: Super Contributor
timestamp: August 24, 2018, 09:51:27 pm
content: Quote from: coppercone2 on August 24, 2018, 08:07:16 pmNo, power dissipation depends on the surface area of the capacitor's physical package. Higher voltage capacitors have a higher ripple current rating because they are physically larger giving them a larger surface area.This is why when replacing old capacitors with new ones which are likely smaller for the same capacitance and voltage rating, a higher voltage capacitor may be necessary to get a physically larger capacitor with the same ripple current rating.QuoteThey could use an electrolyte which does not evaporate as quickly at higher temperature. The thermal resistance from the case to ambient air is pretty high so reducing the thermal resistance inside the capacitor only has a limited effect.

author: TimNJ
author_rank: Super Contributor
timestamp: August 24, 2018, 11:03:43 pm
content: I made a spreadsheet for estimating E-Cap and P-Cap reliability. This one is for an LLC resonant converter, but you can change IRMS formula to work with whatever type of power supply. It might not be 100% accurate but it gives you some sense for what changing different parameters does.More or less the ESR and the can size is what drives the reliability. Lower ESR = lower internal dissipation. Greater can size = more exposed surface area = better heat dissipation.https://docs.google.com/spreadsheets/d/1leHF4NI-vvCjQyNtNhccyEr9aj7icYhoh3UWNlDTyPw/edit?usp=sharing

author: nus
author_rank: Contributor
timestamp: August 25, 2018, 11:09:02 am
content: Nichicon blue and cornell are yellow. So the Nichicon ones are specifically bypass caps, there is also one cornell as a bypass. the rest of the cornell ones are just used around opamps.is this just to do with resonant frequency and impedancethe power rails get fed by LM1117-3.3V transistor

author: Zero999
author_rank: Super Contributor
timestamp: August 25, 2018, 01:43:55 pm
content: Going from the schematic, the ripple current isn't critical. The LM1117-3.3 is not a transistor, but a linear regulator.