ADC errors AN2834
20/49 DocID15067 Rev 3
Figure 16. Analog input with R
AIN
, C
AIN
and C
p
2.2.8 Injection current effect
A negative injection current on any analog pin (or a closely positioned digital input pin) may
introduce leakage current into the ADC input. The worst case is the adjacent analog
channel. A negative injection current is introduced when V
AIN
< V
SS
, causing current to flow
out from the I/O pin. This is illustrated in Figure 17.
Figure 17. Effect of injection current
2.2.9 Temperature influence
The temperature has a major influence on ADC accuracy. Mainly it leads to two major
errors: offset error drift and gain error drift. Those errors can be compensated in the
microcontroller firmware (refer to Section 3.2.8 for the temperature-compensation methods).
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