[sdiy] "Zerolytics"

[Steve Lenham]

On 10/05/2020 17:13, ColinMuirDorward wrote:
> Well now I know where to get technical data, just ask Steve!
> 
> Following your lead I'm checking characteristics of CL31A106KBHNNNE 
> (1206,50v, 10uf, JLC "basic part").
> Here 
> <https://www.datasheet.live/index.php?title=Special:PdfViewer&url=https%3A%2F%2Fpdf.datasheet.live%2Fdatasheets-1%2Fsamsung_electro-mechanics%2FCL31A106KBHNNNE.pdf>, 
> it's looking like we get around -60% capacitance around 12v.

Looks like it.

> Not sure why, but in this 
> <https://www.digikey.ca/en/datasheets/samsung-electro-mechanics/samsung-electro-mechanics-cl_series_mlcc_ds>general 
> catalogue it shows different data for the same part (look for the blue 
> XR5 line on the chart neat the end).

Yes, I saw that document when searching the first time. I think that 
graph is only intended to show the shape of the curve for the different 
dielectric materials; the specific numbers cannot hold for every value 
and voltage rating. I would trust the individual datasheets.

> Assuming the first one is accurate, I guess you could try asking the 
> robot to put down three on each power rail and you'd have your 10uf. But 
> that's quite pointless when you could just pay the $3 "extended part" 
> acquisition fee and get a seven cent electrolytic.

You pays your money and you takes your choice...

cheers,

Steve L.


> 
> On Sat, May 9, 2020 at 6:23 AM Steve Lenham <steve at bendentech.co.uk 
> <mailto:steve at bendentech.co.uk>> wrote:
> 
>     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
> 
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