The working principle of Hall elements
Let's start by learning about the Hall effect to understand the working principle of Hall elements. The Hall effect is a type of electromagnetic effect discovered by American physicist Hall in 1879 while studying the conductivity mechanism of metals. When current passes through a semiconductor perpendicular to the external magnetic field, carriers are deflected, and an additional electric field is generated perpendicular to the direction of the current and magnetic field, resulting in a potential difference at both ends of the semiconductor. This phenomenon is known as the Hall effect, also known as the Hall potential difference.
Hall elements are Hall devices made based on the Hall effect, which use a magnetic field as the working medium to convert the motion parameters of an object into digital voltage output, enabling it to have sensing and switching functions. According to the function of Hall elements, they can be divided into Hall linear elements and Hall switching elements. The former outputs analog signals, while the latter outputs digital signals. 01. The internal components of a linear Hall element mainly include a voltage regulator circuit, a linear Hall element, and an operational amplifier. Its input is magnetic induction intensity, and its output is a voltage proportional to the input quantity. This type of circuit has high sensitivity and excellent linearity, suitable for various magnetic field detection. Linear Hall elements will trigger a parabolic stroke based on the strength of the magnetic field. For example, the acceleration lever of an electric vehicle uses linear Hall elements, which can increase the speed from 0 to the maximum according to the change of the magnetic field. However, when the magnetic field strength exceeds the highest point in a certain range, the speed remains unchanged.
02. Hall switch type Hall sensor consists of a regulator, Hall element, amplifier, Schmitt trigger, and output stage.
When a magnetic object moves closer to the Hall switch, the Hall element on the switch detection surface generates the Hall effect, causing a change in the internal circuit state of the switch, thereby identifying the presence of a magnetic object nearby and controlling the on or off of the switch. The detection object of this proximity switch must be a magnetic object.