To use the maximum dynamic range of the ADC, the input signal must be biased around the mid-scale of the ADC input range. In the ADS816x, where the absolute input range is 0 V to the reference voltage (VREF), mid-scale is VREF / 2. The REFby2 buffer generates the VREF / 2 signal for mid-scale shifting of the input signal. Figure 38 shows that REFBy2 can be used in various types of sensor signal conditioning circuits.
A resistor divider at the output of the reference buffer, as shown in Figure 39, generates the VREF / 2 signal. When not using the internal reference buffer (see the PD_CNTL register), any voltage applied at the REFP pin is applied to the resistor divider. The output of the resistor divider is buffered and available at the REFby2 pin.
The REFby2 buffer is capable of sourcing up to 2 mA of DC current. The REFby2 pin has ESD diode connections to AVDD and GND.