The Hall-effect was discovered by Edwin Hall. Hall discovered that when a current is passed through a conductor that has a magnetic field applied orthogonally, that the Lorentz force can cause a measurable voltage potential across the conductor.

The Lorentz force arises from a charged particle moving through an electromagnetic field as shown in Figure 1-4 and described in Equation 1.

Considering this behavior when driving a current through a magnetic field, we observe the Hall-effect as shown in Figure 1-5.

When a conductive Hall-element is biased with a current and placed in a magnetic field, there is a linear change in the voltage which is produced across the conductor orthogonal to the current. This is particularly useful in generating a number of output formats that aid in tracking the position of a source magnet.

Of particular note here is the switch format. When amplified and driven into a comparator structure like that in Figure 1-6, this voltage can be used to produce a binary output response demonstrated in Figure 1-7. The device can be set to target a variety of operate and release thresholds (commonly referred to a B_OP and B_RP respectively), and can be set to sample at various intervals to limit current consumption.

This technology is easily integrated into semiconductor processes. Traditionally, the Hall-element has been constructed with a sensitivity which is normal to the PCB surface and detect the Z-component of the B-Field vector similar to Figure 1-8, but newer devices are also able to implement in-plane sensing elements which detect a horizontal vector component in either the X or Y directions. This sensitivity is shown in Figure 1-9.