| Electronics > Projects, Designs, and Technical Stuff |
| Is this really a 100uF cap or marketing BS |
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| JustMeHere:
I bought some of these caps (see link) on the idea they were 100uF caps and would work well with the esp32. After testing them, they are all in the 75uF area. So I looked at the spec sheet (linked) and saw in the graph on page 2 that they are only 100uF around 400-500 kHz. Is this common? Should I really consider these 75uF caps? https://ds.yuden.co.jp/TYCOMPAS/ut/download?pn=JMK316ABJ107ML-T++&fileType=Datasheet |
| Prehistoricman:
Page 2 of a 1 page document? :o I also like how their graph stops at 500kHz but the scale continues to 10GHz. |
| amyk:
Ceramic caps have decreasing capacity with increasing applied voltage. |
| Alex Eisenhut:
It's common for ceramic caps to be specified at 0V bias. You'll find you lose a lot of your uF rating with only a few volts bias. I have no idea why the value changes so much with frequency however. The kinds of dielectric to get these high capacitances in such small packages probably have all kinds of undesirable characteristics in the name of higher Dk. To reassure you, they're all like that and Taiyo Yuden is a good brand. There's debate about what's better for decoupling power supplies. I think lower value caps with more predictable specs are better than a capacitor tuned for maximum on only one spec. |
| wraper:
Pretty typical class II ceramic MLCC. Most likely will be used at something like 1-1.5V power rail anyway. And 80% drop of capacitance at rated voltage is far from the worst. Some are left with <10%. EDIT, BTW if you look at capacitance/frequency chart, you may end up with effective capacitance much higher that rated. |
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