Electronics > Metrology

MAX6226 voltage reference

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exe:
Currently logged data. I averaged all values with a sliding window of 1000 measurements. It's still hard to see individual voltages, so I'll re-plot each reference individually.

On Sept 6 I loaded ic1 ic3 ic6 and ic8 with 2.4k resistors (~1.04mA). Vertical black dashed line indicates that moment.

On Sep  1 05:37:45 PM (UTC) there was a 30s power outage in my lab, but I don't see any impact on measurements.

IC2 is a wreck :).

exe:
I'm attaching latest data (extremely averaged so the trend is clear). There is a 5-day gap because script crashed.

From what I see, long-term drift is in spec ("max 11ppm/1000hr Long-Term Drift"). Tempco looks fine too.

I'd say it's good-enough for 4.5digit or may be even 5.5digit portable instruments if environment conditions are stable.

What should I do with it next? Shall I switch it off for one day and then on again to see if there is any hysteresis?

Andreas:

--- Quote from: exe on October 17, 2021, 09:01:55 am ---What should I do with it next? Shall I switch it off for one day and then on again to see if there is any hysteresis?

--- End quote ---
Hello,

if it is related to humidity one day might be not sufficient.
(Its more like 1-2 weeks off time needed here).

I had one reference (ISL21009) which had after a short power interruption (minutes) a nearly 300 uV offset which needed several days to settle again.

with best regards

Andreas

exe:
I unplugged my board for two weeks, then plugged again. The DMM was off as well, but I let it warm up for two days before starting measurements.

I don't see any significant drift except ic2.

One thing I was curious is how bad my cables are. So, when the board was unpowered, it was showing 0.47-0.48mV voltage on output. Touching/moving cables would cause -100uV change, with recovery to within 10uV or so within some tens of second. Not sure if this observation means anything other than my cables suck. 10uV is pretty large value comparing to drift of references themselves.

exe:
Latest data. Periods with less disturbance are when I was absent. I don't know what happened to ic2. It seems it recovered and doesn't suffer excessive drift anymore  :-// .

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