35.3.2.5 Input Voltage Range and Bias Current
In applications where a rail-to-rail input voltage range is not needed, the
            OPAMP peripheral may be configured to save power. Writing ‘1’ to the
            Input Range Select (IRSEL) bit in the Power Control (PWRCTRL) register reduces the
            voltage range of the op amp inputs, which also reduces power consumption. See the
                Electrical Characteristics section for more information about the expected
            voltage range and power consumption.
The bias current of the op amp inputs is the same as the leakage current specified for I/O PORTS in the Electrical Characteristics section.
