8.2.1.1 Design Requirements

Current measurement through the phase of a motor power line is done via the shunt resistor R_SHUNT (in a two-terminal shunt); see Figure 36. For better performance, the differential signal is filtered using RC filters (components R₂, R₃, and C₂). Optionally, C₃ and C₄ can be used to reduce charge dumping from the inputs. In this case, care must be taken when choosing the quality of these capacitors; mismatch in values of these capacitors leads to a common-mode error at the modulator input. Using NP0 capacitors is recommended, if necessary.

Figure 36. Shunt-Based Current Sensing with the AMC1100

The isolated voltage measurement can be performed as described in the Device Functional Modes section.