[sdiy] Using non-linear passives

[Roman Sowa]

W dniu 2017-04-05 o 20:38, Tom Wiltshire pisze:
>
> Ok, in that case, I guess my question would be why call it 4.7uF/35V
> if it isn't?! :)

Because it IS 4.7uF at low voltage and it CAN work at 35V. So if you 
need ceramic cap at 30V or so, you know it needs to be 4.7uF to have 
about 0.5uF at rated voltage. There are of course electrolytics more 
aplicable here, but ceramics have their advantages like size, ESR, 
price, non-polarity, ripple current and in some cases durability.

>
> I notice all the parts talked about are in the uF range, and these
> are very small caps we're looking at. Would this problem decrease for
> smaller values where you're not trying to squeeze so much capacitance
> into such a small package? 220nF? 47nF? 100p?

basicaly the bigger cap physically, the better specs at higher voltage 
one can expect. You can get 1uF at 0201 probably but I think it's more 
like "we're the best, and you can't do that" competition between cap 
makers. Because 1uF at that size would be total crap.

Roman