Ambient magnetic fields will be reflected on the output of the TMCS2100-Q1. A system level DC offset calibration can be done to account for these fields, but a changing magnetic field will create an offset on the TMCS2100-Q1. Figure 4-9 shows the vertical component of the magnetic field coming from a bus bar. The X axis represents the distance from the edge of the bus bar.

Figure 4-9 Field Strength vs Distance

As expected, the closer the devices are to the ambient field source, the bigger the impact there will be. This specific example is assuming the DC+ and DC- cables of a DC source, such as a DC supply for a three-phase traction inverter, see Figure 4-10. The different line colors in Figure 4-9 represent different spacings between the DC+ and DC- links. The closer together the DC link components are routed, the weaker the magnetic field seen by a device nearby. While a system level DC offset calibration can handle static fields, the changing magnetic field from unbalanced or poorly routed power delivery networks will create time-varying measurement offsets. In systems where maximum accuracy is required, DC link cables should be routed as close together as practical—ideally within 5-10 mm of each other—to minimize the external magnetic field environment.

Figure 4-10 DC Bus Bar Setup