Hall effect sensor
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Improving signal-to-noise
Integrating a Hall sensor into a ferrite ring (as shown) concentrates the flux density of the current's magnetic field along the ferrite ring and through the sensor (because flux flows through ferrite much better than through air),[25] which greatly reduces the relative influence of stray fields by a factor of 100 or better. This configuration also provides an improvement in signal-to-noise ratio and drift effects of over 20 times that of a bare Hall device.
The range of a given feedthrough sensor may also be extended upward and downward by appropriate wiring. To extend the range to lower currents, multiple turns of the current-carrying wire may be made through the opening, each turn adding to the sensor output the same quantity; when the sensor is installed onto a printed circuit board, the turns can be carried out by a staple on the board. To extend the range to higher currents, a current divider may be used. The divider splits the current across two wires of differing widths and the thinner wire, carrying a smaller proportion of the total current, passes through the sensor.
Current clamp
A variation on the ring sensor uses a split sensor which is clamped onto the line enabling the device to be used in temporary test equipment. If used in a permanent installation, a split sensor allows the electric current to be tested without dismantling the existing circuit.
The output is proportional to both the applied magnetic field and the applied sensor voltage. If the magnetic field is applied by a solenoid, the sensor output is proportional to the product of the current through the solenoid and the sensor voltage. As most applications requiring computation are now performed by small digital computers, the remaining useful application is in power sensing, which combines current sensing with voltage sensing in a single Hall effect device.
By sensing the current provided to a load and using the device's applied voltage as a sensor voltage it is possible to determine the power dissipated by a device to form a wattmeter.
Motion sensing
Hall effect devices used in motion sensing and motion limit switches can offer enhanced reliability in extreme environments. As there are no moving parts involved within the sensor or magnet, typical life expectancy is improved compared to traditional electromechanical switches. Additionally, the sensor and magnet may be encapsulated in an appropriate protective material.
Ignition timing
Commonly used in distributors for ignition timing (and in some types of crank- and camshaft-position sensors for injection pulse timing, speed sensing, etc.) the Hall Effect sensor is used as a direct replacement for the mechanical breaker points used in earlier automotive applications. Its use as an ignition timing device in various distributor types is as follows: a stationary permanent magnet and semiconductor Hall Effect chip are mounted next to each other separated by an air gap, forming the Hall Effect sensor.
A metal rotor consisting of windows or tabs is mounted to a shaft and arranged so that during shaft rotation, the windows or tabs pass through the air gap between the permanent magnet and semiconductor Hall chip. This effectively shields and exposes the Hall chip to the permanent magnet's field respective of whether a tab or window is passing through the Hall sensor. For ignition timing purposes, the metal rotor will have several equal-sized windows or tabs matching the number of engine cylinders (the #1 cylinder tab will always be unique for discernment by the Engine Control Unit).
This produces a uniform output similar to a square wave since the shielding and exposure time are equal. This signal is used by the engine computer or ECU to control ignition timing.
Anti-lock braking
The sensing of wheel rotation is especially useful in anti-lock braking systems. The principles of such systems have been extended and refined to offer more than anti-skid functions, now providing extended vehicle handling enhancements.
Brushless motors
Some types of brushless DC electric motors use Hall effect sensors to detect the position of the rotor and feed that information to the motor controller. This allows for more precise motor control. Hall sensors in 3 or 4-pin brushless DC motors sense the position of the rotor and to switch the transistors in the right sequence.[26]
Hall-effect thruster
A Hall-effect thruster (HET) is a device that is used to propel some spacecraft, after it gets into orbit or farther out into space. In the HET, atoms are ionized and accelerated by an electric field. A radial magnetic field established by magnets on the thruster is used to trap electrons which then orbit and create an electric field due to the Hall effect. A large potential is established between the end of the thruster where neutral propellant is fed, and the part where electrons are produced; so, electrons trapped in the magnetic field cannot drop to the lower potential. They are thus extremely energetic, which means that they can ionize neutral atoms. Neutral propellant is pumped into the chamber and is ionized by the trapped electrons. Positive ions and electrons are then ejected from the thruster as a quasineutral plasma, creating thrust. The thrust produced is extremely small, with a very low mass flow rate and a very high effective exhaust velocity/specific impulse. This is achieved at the cost of very high electrical power requirements, on the order of 4 kW for a few hundred millinewtons of thrust.
Integrated digital electronics
Hall sensors ICs often integrate digital electronics.
Some Hall sensor ICs integrated a DSP, which can allow more processing techniques directly within the sensor package.[1]: 167
Some Hall sensor ICs integrate an
The ESP32 microcontroller even has an integrated Hall sensor which hypothetically could be read by the microcontroller's internal analog-to-digital converter, though it does not work.[29]
Two-wire interface
Hall sensors normally require at least three pins (for power, ground, and output). However, two-wire ICs only use a power and ground pin, and instead communicate data using different current levels. Multiple two-wire ICs may operate from a single supply line, to further reduce wiring.[30]
Human interface devices
Hall effect switches for
Hall effect sensors can also be found on some high-performance gaming keyboards (made by companies such as SteelSeries, Wooting, Corsair), with the switches themselves containing magnets.[32]
Although Sega pioneered the use of Hall effect sensors in their Sega Saturn 3D controller[33] and Dreamcast stock controller[34] from the 1990s, Hall effect sensors have only started gaining popularity for use in consumer game controllers since the early 2020s, most notably in analog stick/joystick and trigger mechanisms,[35] for enhanced experience due to their contactless, high-resolution, low-latency measurements of position and movement and their longer lifespan due to lack of mechanical parts.
Applications for Hall effect sensing have also expanded to industrial applications, which now use Hall effect joysticks to control hydraulic valves, replacing the traditional mechanical levers with contactless sensing. Such applications include mining trucks, backhoe loaders, cranes, diggers, scissor lifts, etc.
Dual Hall sensor ICs
Some ICs include two Hall elements. This is useful for counting a series of increments (an
See also
References
- ^ ISBN 978-0-7506-7934-3.
- ^ "How the Hall Effect Still Reverberates - IEEE Spectrum". spectrum.ieee.org. Retrieved 2023-12-28.
- ^ "Global Industry Analysts: Global Hall-Effect Current Sensors Market to Reach $1.3 Billion by 2026". www.prnewswire.com. 2021-07-01. Retrieved 2023-12-28.
- ^ a b c d e "Hall Effect Sensor | Applications Guide". www.allegromicro.com. Retrieved 2023-12-28.
- ISBN 978-0-7503-0855-7.
- ^ "Linear Hall Sensors (product category)". TDK. Archived from the original on 2023-02-05. Retrieved 2024-01-02.
- ^ Gilbert, Joe; Dewey, Ray (2022-05-05). "AN27702: Linear Hall-Effect Sensor ICs" (PDF). Allegro MicroSystems. Archived (PDF) from the original on 2023-11-04. Retrieved 2024-01-02.
- ^ https://www.jameco.com/Jameco/Products/ProdDS/2135881.pdf [bare URL PDF]
- ^ "Unipolar Hall-Effect Sensor IC Basics". www.allegromicro.com. Retrieved 2023-12-28.
- ^ "Omnipolar Switch Hall-Effect IC Basics | Allegro MicroSystems". www.allegromicro.com. Retrieved 2023-12-28.
- ^ "Bipolar Switch Hall-Effect ICs". www.allegromicro.com. Retrieved 2023-12-28.
- ^ "AN296067: Hall Effect Switch | Latching Switch Basics". www.allegromicro.com. Archived from the original on 2023-09-27. Retrieved 2023-12-28.
- ^ https://www.elecrow.com/download/A3141-2-3-4-Datasheet.pdf [bare URL PDF]
- ^ https://radiolux.com.ua/files/pdf/SS41F.pdf [bare URL PDF]
- ^ Staff Writer. "How to Decide Between a Reed Switch or a Hall Switch". I.I. Thomas. Retrieved 20 April 2021.
- ^ Hertz, Jake. "Engineers Deal With Drift in Many Ways. What About a "Zero Drift" Hall-Effect Current Sensor?". All About Circuits. Retrieved 20 April 2021.
- ^ Crescentini, M. (2016-09-07). "Experimental Characterization of Bandwidth Limits in Hall Sensors" (PDF). Archived (PDF) from the original on 2023-12-30. Retrieved 2023-12-30.
- ^ Palvik, Scott (2019-08-27). "Differential Hall-Effect Sensors: Safer and More Reliable for Two-Wheelers of the Future". www.allegromicro.com. Archived from the original on 2023-12-30. Retrieved 2023-12-30.
- ISBN 978-3-319-05352-3.
- ^ "ZenFone 5 (A500CG)". asus.com. Retrieved 2 September 2017.
- ^ "Liquid Level Sensing: Measuring Liquid Levels Using Hall Effect Sensors" (PDF). infineon.com. 12 February 2009. Retrieved 2 September 2017.
- ^ Tank Sensors & Probes, Electronic Sensors, Inc., retrieved August 8, 2018
- ^ "Hall probes". Lake Shore Cryotronics. Retrieved 2023-12-29.
- ISBN 978-3-319-05352-3.
- ^ "Hall Effect Sensor | Applications Guide". www.allegromicro.com. Retrieved 2023-12-28.
- ^ Burke, Mary (February 2004). "Why and How to Control Fan Speed for Cooling Electronic Equipment". Analog Dialogue. 38.
- ^ "Hall Effect Sensor Voltage Regulation and Power Management". phareselectronics.com. Archived from the original on 29 May 2015. Retrieved 26 May 2015.
- ^ https://www.mouser.com/c/sensors/magnetic-sensors/?q=I2C or any other part distributor search for "I2C" and "Hall sensor"
- ^ ESP32Technical Reference Manual V4.9 2023 revision history removed mention of the sensor. PCN20221202 gives the following reason for removal: "In the documentation for ESP32 series of products, hall sensor is listed as one of the supported peripherals. However, the hall sensor on ESP32 does not work properly. Therefore, all references to hall sensor in ESP32 documentation need to be removed."
- ^ Burdette, Eric (2021-07-08). "AN296233: TWO-WIRE AND THREE-WIRE SENSOR INTERFACES" (PDF). Allegro MicroSystems.
- S2CID 7540281.
- ^ "Guide to keyboards with Hall Effect switches". hlplanet.com. Retrieved 2023-11-19.
- ^ "A GameCube-style Switch controller without stick drift (Thank god)". 9 January 2023.
- ^ "What is a Hall Effect controller anyway, and do I really need one?". 28 July 2023.
- ^ "Game controllers with hall effect joystick sensors". hlplanet.com. Retrieved 26 July 2023.
- ^ "Dual Hall-effect latch IC with speed and direction - Medium sensitivity". Melexis. Retrieved 2023-12-28.
- ^ "Dual Hall-Effect Latches | Allegro MicroSystems". www.allegromicro.com. Retrieved 2023-12-28.
- ^ https://www.ti.com/lit/ds/symlink/tmag5111.pdf [bare URL PDF]
Further reading
- naveed, A.; Ihn, T.; Ensslin, K.; Papp, G.; Peeters, F.; Maranowski, K.; Gossard, A. C. (2006). "Classical Hall effect in scanning gate experiments" (PDF). S2CID 121163404.
- Nave, R. "Hall Effect". Hyperphysics. Georgia State University Department of Physics and Astronomy. Retrieved 20 April 2021.
External links
- Media related to Hall sensors at Wikimedia Commons