[bsder]

> It is not actually true that MLCC DC bias derating scales with voltage rating. The voltage rating itself actually has nothing to do with it.

This statement used to be false (I used to design boards where I would bump the voltage rating to get better DC bias behavior), but it looks like the engineering behind these capacitors has changed "recently" (as in the last 10 years), and it is now mostly true.

Looking at Murata caps, for example:

1.0uF--uniformly 50% derating from 6-16V:

https://www.murata.com/en-us/products/productdetail?partno=G...

https://www.murata.com/en-us/products/productdetail?partno=G...

https://www.murata.com/en-us/products/productdetail?partno=G...

100nf--uniformly 2% derating from 6-16V:

https://www.murata.com/en-us/products/productdetail?partno=G...

https://www.murata.com/en-us/products/productdetail?partno=G...

https://www.murata.com/en-us/products/productdetail?partno=G...

Interesting. TIL.

Thanks for pointing that out.

[Ductapemaster]

Thank you (and the GP) for the correction! I'll admit this lesson came to me a decade ago and I am speaking to a rule of thumb I developed as a result. Time to update my knowledge banks.

[exmadscientist]

The other thing worth mentioning is that there are multiple formulations, and they're not all equal. Just to pick on Murata, the last character of their part number is a reeling code (something so boring it's often omitted or wildcarded), and then the three characters before that represent the specific dielectric material in use. (Or something like that. It's a private use field and I'm reverse engineering it here.) For the examples above, that's "E01", "A01", or "A88". Each of those will behave differently in SimSurfing, but all parts with the same dielectric code will have the same DC bias behavior. (At least, they will if they have the same size and value, etc. When those change too, behavior still follows the usual trends.)

Parts with different codes can have vastly different behavior under DC bias. You'll find that one of them is the clear winner in most cases. Unfortunately, Murata knows this too, and that one is invariably more expensive in distribution.

But at least you can specify it!

Other vendors do this too, but it's easiest to see with Murata's setup and tools.