9.1.2 Single-Ended Inputs

The ADS1013 and ADS1014 can measure one, and the ADS1015 up to four, single-ended signals. The ADS1013 and ADS1014 can measure single-ended signals by connecting AIN1 to GND externally. The ADS1015 measures single-ended signals by appropriate configuration of the MUX[2:0] bits in the Config register. Figure 25 shows a single-ended connection scheme for ADS1015. 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 ADS101x can only accept positive voltages with respect to ground. The ADS101x do not lose linearity within the input range.

The ADS101x 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.

NOINDENT:

NOTE: Digital pin connections omitted for clarity.

Figure 25. Measuring Single-Ended Inputs

The ADS1015 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 ADS1015 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.