Introduction: This article mainly introduces the principle of Hall switch . Maybe many people have not heard of the Hall switch , but I am sure to be familiar with the Hall effect. Let's learn how the Hall switch works together.
1. Hall Switch Principle - Introduction
Hall switch, also known as Hall digital circuit, is a new type of electrical accessories, including reverse voltage protector, precision voltage regulator, Hall voltage generator, differential amplifier, Schmitt trigger, temperature The compensator and the complementary collector open-circuit output device are composed of seven parts, featuring non-contact, low power consumption, long service life and high response frequency. The internal use of epoxy resin is sealed and integrated into various harsh environments. Reliable work. The circuit is the ideal device for brushless fans due to its load capacity of up to 400 mA and its complementary output.
2. Hall switch principle - structure
The Hall switch circuit consists of a reverse voltage protector, a precision voltage regulator, a Hall voltage generator, a differential amplifier, a Schmitt trigger, a temperature compensator, and a complementary open collector. Below we briefly introduce the functions of each part.
Voltage regulator: When the power supply voltage changes from 3.5V to 20V, the circuit is guaranteed to work normally.
Reverse protector: when the application power is reversed or interfered by the reverse pulse voltage during use, the circuit is protected, and the protection voltage can reach 30V;
Hall voltage generator: converts a varying magnetic signal into a corresponding electrical signal.
Differential Amplifier: Amplifies the weak voltage signal from the Hall voltage generator output.
Schmitt Trigger: Converts the analog signal output from the differential amplifier into a digital signal.
Temperature Compensator: Ensures that the integrated circuit operates reliably between -20 ° C and +85 ° C.
Complementary output: The output current directly drives the two sets of windings of the brushless fan.
As can be seen from the above figure, when the brushless fan is powered on, if the Hall voltage generator is subjected to the alternating magnetic field, the potential states of the output terminals 2 and 3 also change, thereby changing the direction of the load current, so that the fan Normal operation.
3. Hall switch principle
The Hall effect is that when a metal or semiconductor chip with current is placed vertically in a magnetic field, a potential difference occurs at both ends of the sheet, and the potential difference at both ends is called the Hall potential U. Its expression is:
U=KIB/d
Where K is the Hall coefficient, I is the current passing through the sheet, B is the magnetic induction of the applied magnetic field, and d is the thickness of the sheet.
The Hall switch is an active magnetoelectric conversion device. It is based on the Hall effect principle and is fabricated by an integrated package and assembly process. It can easily convert the magnetic input signal into an electrical signal in practical applications. It can also meet the requirements of easy operation and reliability in practical applications in industrial applications.
Under the action of the external magnetic field, when the magnetic induction exceeds the conduction threshold BOP, the Hall circuit output tube is turned on and outputs a low level. After B increases again, the circuit remains in the on state. If the B value of the applied magnetic field is reduced to BRP, the output tube is turned off and the output is high. We call BOP the working point, BRP as the release point, and BOP-BRP=BH as the return difference. The presence of a backlash enhances the anti-jamming capability of the switching circuit.
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