The ADS1113-Q1 and ADS1114-Q1 can measure one, and the ADS1115-Q1 up to four, single-ended signals. The ADS1113-Q1 and ADS1114-Q1 can measure single-ended signals by connecting AIN1 to GND externally. The ADS1115-Q1 measures single-ended signals by appropriate configuration of the MUX[2:0] bits in the Config register. Figure 9-2 shows a single-ended connection scheme for ADS1115-Q1. The single-ended signal ranges from 0 V up to positive supply or +FS, whichever is lower. Negative voltages cannot be applied to these devices because the ADS111x-Q1 can only accept positive voltages with respect to ground. The ADS111x-Q1 do not lose linearity within the input range.

The ADS111x-Q1 offer a differential input voltage range of ±FSR. Single-ended configurations use only one-half of the full-scale input voltage range. Differential configurations maximize the dynamic range of the ADC, and provide better common-mode noise rejection than single-ended configurations.

The ADS1115-Q1 also allows AIN3 to serve as a common point for measurements by appropriate setting of the MUX[2:0] bits. AIN0, AIN1, and AIN2 can all be measured with respect to AIN3. In this configuration, the ADS1115-Q1 operates with inputs, where AIN3 serves as the common point. This ability improves the usable range over the single-ended configuration because negative differential voltages are allowed when
GND < V_(AIN3) < VDD; however, common-mode noise attenuation is not offered.