AN2615 Datasheet, PDF (15/37 Pages) STMicroelectronics – In general the ADC embedded in the ST7 microcontroller

AN2615
Error analysis/constraints
conversion time and the better the accuracy. In conclusion, there is always a trade-off
between conversion time and accuracy.
7.5
16-bit timer
A 16-bit timer is used as the counter that measures the conversion time. Overflows are also
taken into account, so we can also use an 8-bit timer. The resolution of the ADC depends on
the operating frequency of the timer.
7.6
Effect of temperature
The value and characteristics of each component varies with temperature. The effect of
temperature can be broadly categorized as ‘offset drift’ and ‘gain drift’. So we need to
compensate the ADC for each significant change in temperature.
7.7
Comparator
The comparators are the cornerstone of the A/D conversion process. The ability of the
comparator to detect small voltage/current changes makes the comparator very important in
the A/D conversion process. Any degradation of the intended behaviour of the comparator,
which is most usually caused by unwanted noise, leads to the degradation of the ADC’s
ability to measure low voltages.
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