Unipolar Mode

When measuring positive external channels or when the SYSMON measures internal sensors, the ADC operates in a unipolar mode. In this mode, the ADC negative input terminal (V_N) must always be lower than the ADC positive input terminal (V_P). In this mode, the voltage on V_P measured with respect to V_N must always be positive. The V_N input should always be driven by an external analog signal. V_N is typically connected to a local ground or common mode signal. The common mode signal on V_N can vary from 0V to +0.25V (measured with respect to GND). Because the differential input range is from 0V to 1.0V (V_P/V_N), the maximum signal on V_P is 1.25V. See the following figure.

Figure 1. Unipolar Input Signal Range