Frequently Asked Questions

Is it safe to use a polarized electrolytic capacitor as a low-cost alternative to a non-polar electrolytic in a small-signal (-0.7 < V < 0.7) bipolar filtering application? One expert has suggested that polarized caps work fine in both directions at low voltages, but we would like to be sure that there are no serious drawbacks. Thanks.

Your expert is correct. Polarized aluminum electrolytic capacitors can withstand up to 1.5VDC of reverse bias without being seriously damaged.


Please explain for the formula for Temperature Rise within a Capacitor.

Put simply. The temperature rise formula is the rms AC current( ripple) squared times the ESR of the capacitor at the operating frequency divided by a thermal constant multiplied by the surface area of the capacitor.

IF the calculated temperature rise is greater than 10C then the capacitor is being overstressed and will eventualy fail sooner than it should.


How can I meassure the ESR in a practical way?

EIA dictates that ESR must be measured using the bridge method using a test frequency of 120 Hz or 1kHz depending on the type of capacitor so the easiest way to measure ESR is by using a LCR bridge..


Are there special considerations for electrolytic capacitors used at high altitude ( 1/8 atmopshere ) operation ? We are using AFA surface mount series or similiar.

Most Aluminum electrolytic capacitors can be used up to 20000 feet without any problems. Above 20000 feet measures should be taken to prevent the capacitor from failing. Typically the parts have their end seals covered with epoxy to pevent contamination and prevent the electrolyte from being forced out of the container.


How can I find which distributor has the stock I'm looking for?

On the homepage, click on the SEARCH DISTRIBUTOR INVENTORY button.  When prompted, fill in the part numbers (up to 3) and click SEARCH.  You’ll see an immediate display of our authorized distributors that has inventory, and how much they have in stock.


How can I receive a catalog?

Illinois Catalog no longer publishes a complete printed catalog, because we want our customers to always have the most up-to-date information. Our website has the most up to date product data.  Product data can be displayed and printed in different formats, such as an individual part or an entire product line (as was done in our print catalog).


      How can I see any series spec sheets, only?

At  the bottom of the homepage you can select PDF's of catalog products and get a list of all active product lines. You can also any of the search engines by selecting the type of capacitor you are sourcing, such as Electrolytic, then click on the series.


       How can I cross reference competitors products?

From the homepage, select “Search by Competitor Series,” then select the competitor. A list of all the series Illinois capacitor can cross. Select the competitors series code and the Illinois capacitor series will be displayed.


      Is there an easy way to do side by side comparisons of two different IC part numbers?

Yes!  It’s very easy.  From the homepage, click on one of a parametric search buttons, such as “Power Film.”  Narrow your selection with the parametric search tool, then put a check mark in box next to each part number and click the COMPARE button.

Still Have Questions?

If you still don’t see the answers to your questions, email our applications engineering department.