To minimize leakage currents on the analog inputs, leave unused analog and reference inputs floating, or connect the inputs to mid-supply or to AVDD. Connecting unused analog or reference inputs to AVSS is possible as well, but can yield higher leakage currents than the previously mentioned options. REFN0 is an exception; this pin can be accidently shorted to AVSS through the internal low-side switch. Leave the REFN0 pin floating when not in use or tie the pin to AVSS.
GPIO pins operate on levels based on the analog supply. Do not float GPIO pins that are configured as digital inputs. Tie unused GPIO pins that are configured as digital inputs to the appropriate levels, AVDD or AVSS, including when in power-down mode. Tie unused GPIO output pins to AVSS through a pulldown resistor and set the output to 0 in the GPIO data register. For unused GPIO pins on the ADS124S06, leave the GPIOCON register set to the default register values and connect these GPIO pins in the same manner as for an unused analog input.
Do not float unused digital inputs; excessive power-supply leakage current can result. Tie all unused digital inputs to the appropriate levels, IOVDD or DGND, even when in power-down mode. Connections for unused digital inputs are listed below.