The analog inputs are connected to an internal multiplexer and it is always good practice to connect unused analog input channel to ground through a resistor (e.g a 1kohm).
MAX11647
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The MAX11646/MAX11647 low-power, 10-bit, 1-/2-channel analog-to-digital converters (ADCs) feature internal track/hold (T/H), voltage reference, a clock...
Datasheet
MAX11647 on Analog.com
The analog inputs are connected to an internal multiplexer and it is always good practice to connect unused analog input channel to ground through a resistor (e.g a 1kohm).