The TMAG5123 samples the Hall element at a nominal sampling interval of t_PD to detect the presence of a magnetic south or north pole. Between each sampling interval, the device calculates the average magnetic field applied to the device. If this average value crosses the B_OP or B_RP threshold, the device changes the corresponding level as defined in Figure 8-3. The Hall sensor + magnet system is by nature asynchronous, therefore the propagation delay (t_PD) will vary depending on when the magnetic field goes above the B_OP value. As shown in Figure 8-7, the output delay also depends on when the magnetic field goes above the B_OP value.

The first graph in Figure 8-7 shows the typical case. The magnetic field goes above the B_OP value at the moment the output is updated. The part will only require one sampling period of t_PD to update the output.

The second graph in Figure 8-7 shows a magnetic field going above the B_OP value just before half of the sampling period. This is the best-case scenario where the output is updated in just half of the sampling period.

Finally, the third graph in Figure 8-7 shows the worst-case scenario where the magnetic field goes above the B_OP value just after half of the sampling period. At the next output update, the device will still see the magnetic field under the B_OP threshold and will require a whole new sampling period to update the output.

Figure 8-7 Field Sampling Timing

Figure 8-8 shows TMAG5123 propagation delay analysis when a magnetic south or north pole is applied. The Hall element of the TMAG5123 experiences an increasing magnetic field as a magnetic south or north pole approaches the device, as well as a decreasing magnetic field as a magnetic south or north pole moves away. At time t₁, the magnetic field goes above the B_OP threshold. The output will then start to move after the propagation delay (t_PD). This time will vary depending on when the sampling period is, as shown in Figure 8-7. At t₂, the output start pulling the output voltage Low. At t₃, the output is completely pulled down. The same process happens on the other way when the magnetic value is going under the B_RP threshold.

Figure 8-8 Propagation Delay