Input rectifier cap

Things can be extra ugly when you have a mixture of high frequency and low frequency ripple. Many capacitor makers specify the ripple current at each. What I usually do is make sure never to exceed the

If you add a few ceramics to the design, you can have the ESR and ESL keep the high frequency stuff mostly out of the big guys.

Remember that the heat flows are nearly linear in the case of a capacitor on a PCB. The RMS current and the ESR mostly make the heat.

A lot of them only want 12 months life -- don't care what happens after warranty expires :(

Odd you don't have datasheet numbers for this, it was on datasheets I looked at a few weeks ago. Look for a table of multipliers buried in the details, the tables are small, perhaps easy to miss?

An example. Recently I worked through ripple current adjusted for both temp. and frequency for two different brands of caps and the multipliers are a little different. These are 85'C caps.

I built a bank of caps for about 600A ripple current for

Mine has been going for 8yrs now. I doubt it could deliver 350W continuous power.

I also noticed with mine when cleaning it , it has no Common mode choke!! This explained why a TV operating off the same line would get snowy when the PC was on simultaneously. Oddly enough it has all these regulatory approval stickers and it's a Antec supposedly.

Your right it is there. I can double the rms current for 70C ambient. I always thought the 105C specification was for core temperature not ambient. I have been grossly derateing my caps! Oh well live and learn. :-)

"egg friar"? Depends on whether he's wearing his habit, or not ;-) ...Jim Thompson

-- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

That must be one of those weird European cults.

"Hammy the Halfwit "

But a 3000 hour life is no good to anyone - so the usual practice is to use the rated rms ripple for 105C and keep the ambient down to no more than 65C.

With just a bit of luck, the electro will then outlast the equipment.

.... Phil

"MooseFET"

The impedance of a high voltage ceramic cap is waaaaayy more than an electro at SMPS frequencies.

.... Phil

Very good :) Pics here:

Shows how much this is a hobby for me these days, not go near CAD software yet this century. I used to use pcad stuff in the mid-80s, on a new 25k PC-AT box with fancy graphics card, the 'full' 640kB installed we had to add the 128k extra memory for pcad to work as the PC-AT had 'only' 512k memory on the mobo; it was lots and lots of double decker chips, each a

Company paid $19k for a program that came on a 5 1/4 floppy disk, and the pcad parts library was total crap, we had to make all our own. When one used a large X-Y chart plotter because local PCB house didn't do NC drilling, no Gerber machine either.

Grant.

You lumping in the tan whatever losses with ESR? Likely be an issue for me soon, so I plan to put temperature probes in a capacitor bank to derate or shutdown at high temperature -- besides, I'm curious...

Grant.

Yes the ESR I am referring to is the one with the ideal capacitor in series with a resistor.

CORNELL DUBILIER has some Java calculators for calculateing lifetime based on ambient temp and ripple current. Its here for anyone who wants to try it.

The site seems a bit slow mainly when useing firefox. Has anyone else noticed CDE is slow.

Here is an application note on how they calculate the values and how to use the tool.

I plugged in my ripple both 1.3Arms @ 120Hz and 0.8Arms @100kHz, for an inferior capacitor then the panasonic. The results were 0.44W dissapation, Avg core temp 63C Expected life hours 84,000 hr's!! In a max ambient of 50C, reasonable its only a 50W flyback no major heatsources and I'm mounting a small fan in the enclosure.

It isn't too slow here on Firefox. But the applets won't work even though I did enable Java and all that for this site :-(

Same here :( Download + reinstalled Java JRE for it too, no joy.

Unless it wants the full Java development kit installed, I lost interest...

Grant.

Yea I should have mentioned it doesn't work with Fire Fox. It does work with IE...... I know Blah :-)

I found it handy even if I'm not using the caps they have loaded in the tool it gives you an idea quickly on any similar cap.

Or if you couldn't be bothered the application note shows how they make the calculations and you can just do it up in Math CAD or excel.

I have noticed the site doesn't seem Fire Fox friendly, even downloading data sheets is problematic. They claim the site is FF compatable. I'm sure they did rigorous testing after all CDE is a huge multimillion $ corporation. So the only logical conclusion is we are doing something wrong;-)

For the record I do have JRE installed and it still doesn't work with FF, it does work with IE.

They do recommend using either IE or Netscape for the tool. The site does however claim to be compatible with FF.

Hammy Inscribed thus:

Mmm ! Works fine for me in "Opera, Firefox & Konqueror"...

=20

=20

interest...

No joy here. Not in wine nor in native linux. Sun Java 1.6.x both cases.

issue=20

bank=20

curious...

else

interest...

BZZZt. The executive managers making such declaration have no such direct knowledge. Including the CITO and the CIO.