According to document IMX25AEC, there is an error of ± 2%FS in the Touchscreen ADC.
Because it is 12 bits, there is an error in 4,096* (+-0.02) = ± 82LSB.
It is very bigger than DNL and INL, is it really so?
Please tell me.
The accuracy parameters of the i.MX25 integrated ADC are described in details in
the AN3948, available on the i.MX25 Documentation web page:
The ADC accuracy is described in terms of Differential and Integral non-
linearity and referenced to the full-scale voltage that is equal to the
reference voltage. So, the ADC conversion accuracy also depends on the reference
voltage stability. The i.MX25 ADC module incorporates the reference voltage
source of 2.5V, however, it is quite inaccurate (about ± 5%). So, to achieve
maximum conversion precision, it is recommended to use an external high-
stability and low-noise reference voltage supply.
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