The AMC1303 is optimized for usage in current-sensing applications using low-resistance shunts. However, the device can also be used in isolated voltage-sensing applications if the effect of the (usually higher) value of the resistor used in this case is considered. For best performance, TI recommends using the ±250-mV versions of the device (AMC1303x25xx) for this use case.
Figure 55 shows a simplified circuit typically used in high-voltage-sensing applications. The high value resistors (R1 and R2) are used as voltage dividers and dominate the current value definition. The resistance of the sensing resistor R3 is chosen to meet the input voltage range of the AMC1303. This resistor and the differential input resistance of the AMC1303x25x is 22 kΩ also create a voltage divider that results in an additional gain error. With the assumption of R1, R2, and RIND having a considerably higher value than R3, the resulting total gain error can be estimated using Equation 4, with EG being the gain error of the AMC1303.
This gain error can be minimized during the initial system-level gain calibration procedure.