Hello everyone, I am designing a circuit using a LTC3588 chip and in the datasheet(page 14 bottom most picture) there is a diagram I am using to help me. In the diagram it specifies voltages for the capacitors; my question is the voltage rating of a capacitor is only to specify the safe voltage right? it won't have any effect if I use a higher voltage specified capacitor. I am pretty sure it doesn't make a difference, but I just wanted to be sure. Also the diagram shows a bipolar 100uF capacitor rated for 16V how is that possible; not many bipolar caps are rated that high and if they are they are huge right?
The correct name for this capacitor is non-polarized and they are commonly found in speaker cross-over networks. You can make a non-polarized capacitor out of 2 standard electrolytic caps by wiring them in series + to +, or - to -. Keep in mind that to get the capacitance you desire, equal value capacitors in series divide in half. So, if you want a 100mfd non-polarized cap, (value seems very high), just wire two 200mfd caps in series, (like poles together). The voltage rating of each cap can be half of the value specified for the original cap since the voltage is applied across both caps equally.
The voltage rating on the cap is generally considered the “working voltage” of the cap and shouldn’t be exceeded. If the highest voltage in a circuit you are designing, for example, is 12VDC, you would typically use a cap rated 15-16VDC. If you need a 1MFD cap at 15VDC, for example, and all you had at 1AM was a 1MFD at 25VDC, no problem, go ahead and use it. If, however, you had a 1MFD at 350VDC, I wouldn’t use it. The reason is, over extended use, the reduced voltage tends to make the capacitor deform and it’s value would change. Also, the +/- tolerance on high voltage caps is typically not as tight as on low voltage caps, so a cap marked at 1MFD could be off pretty far making you wonder why your circuit doesn’t work right.
