Hall effect sensor is a transducer that varies its output voltage in response to changes in magnetic field. Hall sensors operates based on the principle of “Hall Effect”. Hall-effect sensor ICs are used for highly accurate gear-tooth sensing, direction detection, linear sensing, speed sensing, position sensing, contactless proximity switching, positioning, speed detection, and current sensing applications.

Operating Principle of Hall Effect Sensors

The Hall-Effect principle is that when a conductor or semiconductor with current flowing in one direction was introduced perpendicular to a magnetic field, a voltage could be measured at right angle to the current path. Electricity carried through a conductor will produce a magnetic field that varies with current, and a Hall effect sensor can be used to measure the current without interrupting the circuit. Typically, the sensor is integrated with a wound core or permanent magnet that surrounds the conductor to be measured.

Hall Effect Sensors are available with either linear or digital outputs. Frequently, a Hall sensor is combined with circuitry that allows the device to act in a digital (on/off) mode, and may be called a switch in this configuration.

In its simplest form, the hall sensor operates as an analogue transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the relative position of the magnet can be deduced.

For digital system designs, Hall effect sensor may require analog circuitry to be interfaced to microprocessors. These interfaces may include input diagnostics, fault protection for transient conditions, and short/open circuit detection. It may also provide and monitor the current to the hall effect sensor itself.

Applications of Hall Effect Sensors

  • Automotive and Industrial electronics such as the pictured pneumatic cylinder.
  • Computer printers use hall effect sensors to detect missing paper and open covers.
  • Hall effect sensors are used in high-reliability computer keyboards.
  • Hall sensors are commonly used to time the speed of wheels and shafts, such as for internal combustion engine ignition timing, tachometers and anti-lock braking systems.
  • Hall effect sensors are used in brushless DC electric motors to detect the position of the permanent magnet.
  • Hall sensors are used to regulate the speed of hard disc drives.