The bypass capacitor should be placed near the TMAG5124-Q1 to reduce noise. The TEST pin must be connected directly to the GND pin. It is good practice to connect the pins under the package to reduce the connection length.

Generally, using PCB copper planes underneath the TMAG5124-Q1 device has no effect on magnetic flux and does not interfere with device performance. This is because copper is not a ferromagnetic material. However, if nearby system components contain iron or nickel, they may redirect magnetic flux in unpredictable ways.