1 Hall Element Block Count

For encoding applications, binary output devices like latches or switches are used. Within a latch, a single Hall element or an averaged group of Hall elements may be used to measure the field along a single sensing axis. Downstream of the Hall element block within the latch device will be a comparator circuit that determines whether the transduced signal exceeds B_OP or falls below B_RP, thereby producing an output that is either high or low. If the ring magnet or linear array magnet is designed to move in only one direction, then the position can be determined. However, for systems in which the magnet can reverse direction (see Figure 1-1), the device output alone provides insufficient information to definitively determine position.

Consequently, Figure 1-2 shows how a minimum of two latches are used to determine not only position but speed and direction. In the past, this might have been implemented with two discrete devices (see Figure 1-3); however, recent devices have evolved such that a single device may have two distinct Hall element blocks that measure the field at two independent locations (see Figure 1-4). This advancement has led to a reduced bill of materials (BOM) count, reduced board size, and minimized design complexity.