[sdiy] "Zerolytics"

[Steve Lenham]

On 08/05/2020 17:31, ColinMuirDorward wrote:
> Thanks for spelling that out for me, Steve!
> 
> It only occurred to me to try 10uf ceramic when I noticed them available 
> in the "basic parts" catalog at JLCPCB.
> The one I'm looking at is "CL21A106KAYNNNE". It's $0.03, 25v, X5R, 0805. 
> I'm looking through the datasheet 
> <https://datasheet.lcsc.com/szlcsc/Samsung-Electro-Mechanics-CL21A106KAYNNNE_C15850.pdf>and 
> can't find anything to describe it's voltage dependent characteristics. 
> Do I not know what I'm looking for, or do they leave that bit out?

With apologies to Douglas Adams:

“But the voltage dependency characteristics were on display…”
“On display? I eventually had to go down to the cellar to find them.”
“That’s the display department.”
“With a flashlight.”
“Ah, well, the lights had probably gone.”
“So had the stairs.”
“But look, you found the data, didn’t you?”
“Yes,” said Arthur, “yes I did. It was on display in the bottom of a 
locked filing cabinet stuck in a disused lavatory with a sign on the 
door saying ‘Beware of the Leopard.”

That document you linked to is more of a brochure than a datasheet. It 
lists the hundreds of MLCC capacitors that Samsung make without much in 
the way of parameters for each one. There is usually an individual 
datasheet for each cap but it is not always easy to find.

I Googled for that exact part number and, interestingly, most of the 
results were for distributors and none for Samsung themselves. 
Undeterred, I tried the datasheet offered by Farnell - and found that it 
identified itself as a "Spec Sheet" and contained no graphs or 
characteristic data.

Eventually, Digikey provided this "Characteristics" sheet, which is what 
I was looking for:

https://media.digikey.com/pdf/Data%20Sheets/Samsung%20PDFs/CL21A106KAYNNNE_Char.pdf

Have a look at graph 3. It shows that this 10uF/25V cap drops to around 
2uF with 12V DC bias and around 1uF with 20V.

Cheers,

Steve L.
Benden Sound Technology