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# Thermal stability measurements - zero voltage drift.
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Following picture shows the ADC measurements done for 300 s period just
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after turning the power supply on (the board is not warmed up at the
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beginning, no signal attached to the input, offset set to zero).
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y-axis is the voltage measured by ADC (scaled to the input voltage
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range). Each point is the average of 64 samples (to remove the noise
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from the
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signal).
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[](https://www.ohwr.org/project/fmc-adc-100m14b4cha-hw/uploads/a73f82a67bfd4ef82b443809e0c5e520/temp.jpg)
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*Conclusion**
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For the 100 mV range, the the voltage has hanged from 210 uV to 165 uV
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which gives the 45 uV change. Relating to the full scale it is 0.045 %,
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and about 7.5 LSBs.
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For 1 V range, voltage drift is 100 uV (about 2 LSBs) and for the 10 V
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range the drift is almost invisible.
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The results of the measurements are fully satisfying.
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Full temperature measurements, where the input is connected to precise
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voltage source, and the offset compensates it, would be done soon.
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-----
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Maciej Fimiarz - September 2010
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