Millimeter-level displacement detection for reliable smart door locks

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Abstract: Smart door locks are advanced locking systems that offer enhanced user identification, security, and management compared to traditional mechanical locks. As a critical component of smart access control systems, they provide a more secure and convenient way to manage entry. This article explores the use of the Shiqiang-authorized linear Hall sensor MLX90251 in modern smart lock applications.

Smart Lock System

Figure 1 presents the block diagram of the entire smart lock system developed by Shiqiang. The system relies on precise control of the latch’s displacement to operate the door lock effectively. Traditional methods such as photoelectric switches or mechanical limit switches have been used for position detection, but they often suffer from low accuracy and large physical size, which limits their suitability for compact smart lock designs. The linear Hall sensor from Shiqiang addresses these challenges with its small form factor and high precision. It allows for accurate millimeter-level position detection by simply embedding a small magnet on the latch, making it ideal for smart lock applications.

Figure 1: Smart Lock Block Diagram

Features of Linear Hall Sensor

The MLX90251, a CMOS-based programmable high-performance Hall sensor from Melexis (distributed by Shiqiang), provides an analog output proportional to the magnetic field strength. It includes integrated digital signal processing (DSP), programmable filtering, and temperature compensation features, ensuring stable and accurate performance under various conditions. Additionally, the output voltage can be adjusted as needed, offering great flexibility in system design. More detailed technical information and application examples can be found on Shiqiang’s e-commerce platform.

Figure 2: Application Circuit for Linear Hall Sensor

Conclusion

The MLX90251 linear Hall sensor from Melexis, available through Shiqiang, offers significant advantages such as high precision, excellent sensitivity, low power consumption, and flexible design options. It is well-suited for applications like displacement detection in smart door locks. Its simple and reliable circuit design requires only two capacitors and one resistor, making it an efficient and cost-effective solution for modern smart access systems.