Switching and absolute sensors
The first hall effect sensors were switching sensors, the sensor switch when the magnet field strength passes the specified threshold value. Switching hall effect sensors can be used as a stand-alone sensor, a typical application is proximity switch. Or be integrated with an incremental transducer, by combining sensor element and magnet with special characteristics. Typical applications are magnetic encoders and gear tooth sensors.
The basic absolute analog sensor is a radiometric sensor, the output is proportional to the magnet field strength and orientation. This is the basic operation of all analog hall effect sensors, but today they are available in a wide range of options. Analog sensors are used in linear and rotary transducers that come with different characteristics such as output signal, programmable parametrics, supply voltage etc. Analog sensors are used in many applications such as linear positioning, steering-angle, clutch control etc.
2D and 3D sensors
Traditional one-dimension sensors only sense magnetic field perpendicular to the sensor element. This require precise positioning and motion of the magnet, the tolerance for airgap, magnet movement etc is low. As well as material properties such as variation in magnetic flux between magnets, temperature variations etc.
Two or three dimension sensors senses magnetic field in two or three dimensions; X,Y and Z. This is useful in true multi-dimension sensing in ex. joysticks. But also enables a more robust and accurate positioning in rotary and linear transducers.