The input stage of an Analog-to-Digital converter can be modeled with a resistor and a capacitance versus ground. So if the voltage source does not have a low impedance, an error in the measurement of the amplitude will occur. In this condition a buffer is needed to drive the ADC. The LMP8645 has an internal output buffer able to drive a capacitance load up to 30 pF or the input stage of an ADC. If required an external lowpass RC filter can be added at the output of the LMP8645 to reduce the noise and the bandwidth of the current sense. Any other filter solution that implies a capacitance connected to the R_G pin is not suggested due to the high impedance of that pin.

Figure 7-2 LMP8645 to ADC Interface