Sujet : Re: Practical resistor accuracy distribution
De : jjSNIPlarkin (at) *nospam* highNONOlandtechnology.com (John Larkin)
Groupes : sci.electronics.designDate : 27. Apr 2024, 23:24:43
Autres entêtes
Organisation : Highland Tech
Message-ID : <ksqq2jthglli8duia5nd78scf6o0mv4nar@4ax.com>
References : 1 2 3 4
User-Agent : Forte Agent 3.1/32.783
On Sat, 27 Apr 2024 16:47:29 -0400, Joe Gwinn <
joegwinn@comcast.net>
wrote:
On Fri, 26 Apr 2024 19:38:07 -0700, John Larkin
<jjSNIPlarkin@highNONOlandtechnology.com> wrote:
>
On Fri, 26 Apr 2024 20:16:48 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:
>
On Sat, 27 Apr 2024 00:54:41 +0200, Klaus Vestergaard Kragelund
<klauskvik@hotmail.com> wrote:
>
Hi
>
I needed to look into distribution of accuracy of resistors.
>
Vendors don't have any info, but luckily some nice people online have
done measurements:
>
<https://www.eevblog.com/forum/projects/smd-resistor-distributions/>
>
<https://lambdafox.com/resistor-tolerances/>
>
The thing to be aware of is that resistor value distributions are
often wildly non-Gaussian. The classic example is where there are
grades, say 1%, 5%, and 20%. The 5% group will often have a hole that
happens to match the 1% distribution perfectly.
>
A lot of modern resistors are made with a relatively wide
distribution, and then machine-sorted into bins. In this case, many
of the bins will have uniform distributions. And so on.
>
Joe Gwinn
>
I suspect that they may laser trimmed and shipped, not binned.
>
One batch on a reel could be very close to one another.
>
Also possible, and maybe a combination of both?
>
But the fundamental point is that one must measure to be sure, unless
one is a large enough customer that the manufacturer will simply tell
you.
>
Joe Gwinn
We just assume that all 1% resistors are within 1%.
We buy 0.1% and some 0.05% parts too. Since most of our products have
software-based calibration, we mostly care about resistor tempcos, not
so much tolerances.