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I was wondering how high can the capacitance get at a 0402 capacitor for 5V applications aka at least 10V rating (thinking about decoupling capacitors). I checked the filters at mouser, and saw a 22uF capacitor, but this was the only listing (only one capacitor showed up). So I thought something is wrong, why other manufacturers don't make 0402 22uF caps @10V?

screenshot from the two results (voltage rating I chose from 10V and above):

mouser screenshot

scrrenshot mouser

I ignored the non-stock one and checked the datasheet from GRM158R61A226ME15D and noticed how its capacitance is rated:

capacitance rating

Was it really rated at 0.5V bias? (I cant understand the Frequency part. Was it a PWM of 120Hz at 0.5V)?

For the above reasons combined (the only 22uF 10V cap and a weird voltage rating) I am pretty sure this capacitor is poorly rated, and its capacitance is significantly reduced when used at 5V.

Did I miss something else on the datasheet about the voltage rating? What is this 0.5V @ 120Hz testing?

would this X5R capacitor be a good choice for a decoupling capacitor, or its capacitance will be lower due to a poor rating?

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    \$\begingroup\$ 22 μF is a lot of capacitance in such a small size. \$\endgroup\$
    – Hearth
    Oct 12, 2021 at 14:25
  • \$\begingroup\$ Hm what do you mean? I was thinking the less ESR smaller packages provide, thats why I am looking this one. Could this larger capacitance be a problem in such a small capacitor size? After all, as Justme answered, it drops at 3.3uF @5V \$\endgroup\$ Oct 12, 2021 at 14:34
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    \$\begingroup\$ You get lower ESR in larger packages, not smaller. And it's hard to cram a lot of capacitance into a really small area, so you end up with lower voltage ratings and worse dielectrics as well. \$\endgroup\$
    – Hearth
    Oct 12, 2021 at 14:48

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The method of how they are rated is made public so you know the method. Yes, it has been rated with an LCR meter with 0.5V bias. Most likely just a standard sine wave.

If you use Murata SimSurfing website, you can see that at 5V DC bias voltage the capacitance has dropped to 3.3 uF. If that capacitance is acceptable for your 5V decoupling the you can use it, but not if you need more capacitance. Please note that usually decoupling caps are already derated so if a circuit calls for a 10uF capacitor then 10uF capacitor is OK and there may be mention of size or voltage rating. If however a circuit calls for 10uF of capacitance then you have to derate yourself and put a larger or multiple capacitors.

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  • \$\begingroup\$ Ceramic capacitors have a very strong voltage coefficient. While a capacitor may be rated for 10 V (e.g. its breakdown limit is above 10 V), the capacitance you would measure with 10 V could be as low as 20 % of the 'label' value. The actual variation with voltage does depend on the specific ceramic dielectric. See en.wikipedia.org/wiki/… \$\endgroup\$
    – jp314
    Oct 12, 2021 at 15:49

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