Linear Hall effect sensors measure the strength of a magnetic field and output a voltage proportional to that measurement. Based on the degree range and resolution needed, one or more linear Hall sensors can be used to determine the magnet direction. This application report covers angle measurements using no calibration, peak calibration, lookup table calibration, and a hybrid method of both the peak calibrated and lookup table methods.

The two main types of magnetization in permanent magnets are axial and diametric. This terminology makes most sense when talking about discs, cylinders, and ring magnets. Axial magnets have north and south poles that are on the flat surfaces of the magnet. Diametric magnets have north and south poles that are on the rounded edges of the magnet.

Some examples of axially magnetized magnets are the two left magnets in Figure 2-1 and the two left magnets in Figure 2-2.

Some examples of diametrically magnetized magnets are the two right magnets in Figure 2-1 and the two right magnets in Figure 2-2.

Other magnet types are typically referred by shape, such as block and sphere magnets (Figure 2-3 and Figure 2-4), or by unique polarity, for example a multipole ring magnet (Figure 2-5).

When using linear Hall effect sensors to measure angles, a bipolar sensor is generally most practical to use, although unipolar sensors can still be used for limited-angle measurements. Bipolar sensors respond to both the north and south poles of a magnet, and allow for wider-angle measurements. Unipolar sensors respond to one pole of the magnet allowing for only half of the movement range. The following subsections list some of the linear Hall effect devices from TI.

The DRV5053 is a chopper-stabilized Hall effect sensor that offers a magnetic sensing solution with superior sensitivity stability over temperature and integrated protection features.

The 0-V to 2-V analog output responds linearly to the applied magnetic flux density, and distinguishes the polarity of magnetic field direction. A wide operating voltage range of 2.5 V to 38 V with reverse polarity protection up to –22 V makes this device suitable for a wide range of industrial and consumer applications.

Internal protection functions are provided for reverse-supply conditions, load dump, and output short circuit or overcurrent.

The DRV5053-Q1 is the automotive-grade version of the DRV5053.

The DRV5055 is a linear Hall effect sensor that responds proportionally to magnetic flux density. This device can be used for accurate position sensing in a wide range of applications.

The device operates from 3.3-V or 5-V power supplies. When no magnetic field is present, the analog output drives half of VCC. The output changes linearly with the applied magnetic flux density, and four sensitivity options enable maximal output voltage swing based on the required sensing range. North and south magnetic poles produce unique voltages.

Magnetic flux perpendicular to the top of the package is sensed, and the two package options provide different sensing directions.

The device uses a ratiometric architecture that can eliminate error from VCC tolerance when the external analog-to-digital converter (ADC) uses the same VCC as a reference. Additionally, the device features magnet temperature compensation to counteract magnet drift for linear performance across a wide –40°C to +125°C temperature range.

The DRV5055-Q1 is the automotive-grade version of the DRV5055.