The ADS1291, ADS1292, and ADS1292R analog input is fully differential. Assuming PGA = 1, the differential input (INP – INN) can span between –VREF to +VREF. Note that the absolute range for INP and INN must be between AVSS – 0.3 V and AVDD + 0.3 V. Refer to Table 10 for an explanation of the correlation between the analog input and the digital codes. There are two general methods of driving the ADS1291, ADS1292, and ADS1292R analog input: single-ended or differential, as shown in Figure 20 and Figure 21. Note that INP and INN are 180°C out-of-phase in the differential input method. When the input is single-ended, the INN input is held at the common-mode voltage, preferably at mid-supply. The INP input swings around the same common voltage and the peak-to-peak amplitude is (common-mode + 1/2 VREF) and (common-mode – 1/2 VREF). When the input is differential, the common-mode is given by (INP + INN) / 2. Both INP and INN inputs swing from (common-mode + 1/2 VREF to common-mode – 1/2 VREF). For optimal performance, it is recommended that the ADS1291, ADS1292, and ADS1292R be used in a differential configuration.