7.3.6 Propagation Delay

The DRV5015 samples the Hall element at a nominal sampling interval of every 16.67 µs to detect the presence of a magnetic north or south pole. At each sampling point, the device takes the average of the current sampled value and immediately preceding sampled value of the magnetic field. If this average value crosses the B_OP or B_RP threshold, the device output changes to the corresponding state as defined by the Overview section.

Figure 17 shows the DRV5015A1 propagation delay analysis in the proximity of a magnetic south pole. The Hall element of the DRV5015 experiences an increasing magnetic field as a magnetic south pole approaches near the device. At time t₂, the average magnetic field is (B₂ + B₁) / 2, which is below the B_OP threshold of the device. At time t₃, the actual magnetic field has crossed the B_OP threshold. However, the average (B₃ + B₂) / 2 is still less than the B_OP threshold. As such, the device waits for next sample time, t₄, to start the output transition through the analog signal chain. The propagation delay, t_d, is measured as the delay from the time the magnetic field crosses the B_OP threshold to the time output transitions.

Figure 17. Propagation Delay