Hall sensor components are also used in brushless motors of electric vehicles; In aꩵddition, several Hall sensors are also installed on the automatic tool holder of the CNC lathe, indicating that Hall sensors are widely used in our daily production and life. Below, I would like to use this topic to chat with friends about some issues related to Hall sensors.

1、 The Origin of Hall Sensors

Hall sensor is a type of sensor made from semiconductor materials based on the Hall effect. This Hall is actually a personal name. He was an American physicist who discovered through many experiments over a hundred years ago, in 1879, that a constant electric current was passed through a thin metal sheet, and then the sheet was placed in a magnetic field. At this time, he discovered that voltage would appear on the oth🧜er sides of the metal. This voltage is related to the magnetic field. When the magnetic field is strong, the voltage is high, and when the magnetic field is weak, the voltage is low. At that time, due to technological limitations, no materials similar to silicon semiconductors had been discovered, so the voltage obtained using metals was relatively low. It was not until the late 1940s that the Hall effect gradually entered practical applications with the emergence of silicon semiconductors.

Later, people named this sensor after Hall in honor of his contributiওons in this field. Nowadays, most people use semiconductors as the material for Hall sensors. When we apply current to it, voltage is generated in the direction perpendicular to both the current and magnetic field. We call this phenomenon the Hall effect. We refer to this sensor made using the Hall effect as a Hall sensor.

2、 The Principle and Structure of Hall Sensors

We will take a semiconductor Hall element as an example to illustrate its working process. We apply current I to the semiconductor Hall element, and then place this semiconductor wafer in a magnetic field with a magnetic field strength of B. At this time, the electrons in the semiconductor will be subjected to a magnetic force F and move inward. Therefore, a lot of electrons will accumulate on the inner side. As the electrons accumulate more and more, an electric field will be formed at this time. When electrons are subjected to both magnetic and electric field forces, and if the two forces reach a dynamic equilibrium, the accumulation of electrons also reaches a dynamic equilibrium, a vol⛄tage is established. We call this voltage the Hall electromotive force, which is generally represented by Eh. Therefore, the Hall electromotive force Eh can be represented by Eh=KIB. From this equation, it can be seen that K is the sensitivity of the Hall element, and I and B respectively represent the incoming current and the magnetic field strength. Therefore, we know that under a certain incoming current, the stronger the magnetic field strength, the greater the induced Hall electromotive force.

We can know through experiments that the voltage output by Hall elements alone is very small, and we also know that semiconductor devices are easily affected by temperature. Therefore, current Hall sensors generally incorpꦰorate Hall elements, amplifi𝓡ers, temperature compensation circuits, and voltage stabilizing power supplies into a single chip. In terms of the structure of Hall elements themselves, they are generally composed of semiconductors, thin films, substrates, and leads.

3、 The Role of Hall Sensors

After we understand the principle of Hall sensors, we can know their functions. Firstly, they can be used to detect changes in external magnetic fields, and c💛an also be made into contactless sensors. For example, there is a proximity switch made of Hall sensors, which can detect magnetic objects. We know that Hall sensors can generally be divided into two types: linear and switching. For linear Hall sensors, there is a linear relationship between them and the strength of the external magnetic field. For example, the Hall element in the handle of our battery car is a linear Hall sensor used; For switch type Hall sensors, their output is similar to the on and off of switches, which means they can output "1" and "0". For example, the Hall sensors used in CNC lathe tool holders are switch type, mainly used to detect whether the turning tool is in place. In addition, Hall sensors can also be used in measuring displacement, pressure, and other aspects. Generally, we commonly use Hall sensors such as CS-3000 series, SH-100 series, HK series, etc.

4、 Hall sensor detection

We know that Hall sensors will output a voltage signal from th🌃e output terminal when there is a magnetic field approaching, so we can measure the voltage change at the output terminal to determine whether the Hall sensor is normal. We know that in the integrated Hall sensor, it is usually the open collector output type, so we need to add a current limiting resistor when testing its quality. During normal operation, the output pin "3" of the Hall sensor should be at a high level, which is generally close to the power supply voltage Vcc. When we use a small magnet to approach the digital side of the Hall sensor, if the voltage indicated by the multimeter drops below 0.6V, it indicates that the Hall sensor is good. If the voltaꩲge indicated by the multimeter still does not decrease when the small magnet has come into contact with the digital side of the Hall sensor, then switch the magnetic poles of the magnet and try again. If the multimeter indicates a decrease of less than 0.6V at this time, it also indicates that the Hall sensor is good. If the voltage of the multimeter does not decrease in both positive and negative directions, it indicates that the Hall sensor is damaged and cannot be used.