Electronics > Metrology

MAX6226 voltage reference

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Kleinstein:
There is quite some correlation between the references. Unless there is a prblem with the supply, chances are this could be an effect of the meter or maybe thermal EMF from the cables. What meter is used for the measurement ?  Looks like it has a good ref. with low popcorn noise.

The dead bug mounted refs look good.

exe:
The meter is K2000 which was probably re-capped by previous owner(s). K2000's manual says it has 1ppm/C coefficient on 10V .
I too noticed correlation, and I don't know if it because of the meter, because all references exhibit similar tempco :). Or may be leads are not very good.

As of IC1 and IC2, those were subject to freezing well below zero (I used a freeze spray), then hotair, then I physically knocked it with quite some force (I wanted to see how sturdy is ceramic carrier), they were also resoldered at least once... May be that's why IC2 is not doing well :).

I kept the lab with closed window over night, so  there is not much temperature and humidity variation. Tomorrow I'll probably leave the window open to see how that will affect measurements. The downside is, this can create drafts.

After about a week or so I plan to load one or two references with a 2.4K resistor (~1.04mA current) to see load regulation.

Andreas:

--- Quote from: exe on August 24, 2021, 07:49:52 pm ---K2000's manual says it has 1ppm/C coefficient on 10V .

--- End quote ---

Hello,
where exactly do you read this?

I read:
for 18-28 deg C the tempco is within uncertainity specs.
outside of 18-28 deg C the TC is 2 ppm of reading/K (2,5V in your case = 5 uV/K) + 1 ppm of range/K (10V = 10uV/K) or a total of up to 15 uV/K for this measurement.
I fear you will have to do some T.C. measurements of the instrument first.
See:
https://www.eevblog.com/forum/metrology/project-pimp-a-keithley-2000/msg1106829/#msg1106829

with best regards

Andreas

exe:
2Andreas: oh, right. There is no spec for it. Well, then I can't really say anything about precision of this instrument. Even if I find a cal lab (probably I'll have to send it to Germany as local labs turned me away because I'm not a company), I guess they charge me extra for climate chamber.

exe:
Current state of references.

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