Hello Albin, The temperature variation can be found in Figure 39 of the datasheet. Please note that the input impedance is closely approximated as a linear resistance, but there are non-linearities as well (input current verses input voltage is not a straight line, but a curve). In order to minimize the effects of the input non-linearities, the differential resistance of the input source should be 100Ohm or lower in order to meet the datasheet specification for INL. Keeping the source impedance low will also reduce any gain errors as well. For this reason, we do not recommend using a high input impedance, such as a voltage divider, to directly drive the ADC inputs if DC precision (gain, linearity, offset) are important. We do not have any long term drift data specific to input impedance, but a good estimate of input impedance drift over a 10yr period will be approximately equal to the maximum temperature drift. For example, in high-speed mode, you can expect the input resistance to change by 300Ohm from 25C to 125C. You can also expect the input resistance to change by about 300Ohm over a 10yr operating period. This shift would be in addition to the temperature drift change. Regards, Keith
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