Compared with Hall ICs, AMR sensors offer greater flexibility in magnet placement and orientation, enabling designs tailored to specific applications. Conventional Hall IC designs often use a magnet positioned above the sensor. In contrast, because AMR sensors are sensitive to a different magnetic-field direction than conventional Hall ICs, they offer greater flexibility in magnet placement and orientation. This makes it easier to design layouts that match device structures and design constraints, helping achieve a stable switch design.
Compared with reed switches, AMR sensors have less variation in detection characteristics, helping reduce unit-to-unit variation in detection distance and position during mass production. This helps reduce the effort required to adjust magnet and sensor positions and helps stabilize detection timing across final products. Because AMR sensors are contactless, concerns about contact wear and chattering are eliminated, helping maintain stable switching over the long term.
Murata's AMR sensors are magnetic sensors that can control ON/OFF states based not only on magnetic-field strength or presence, but also on magnetic-field direction.
Properly understanding the characteristics of AMR sensors and optimizing magnet and sensor placement helps suppress unintended ON states and achieve reliable switching.
With conventional magnetic sensors, the OFF condition may require the magnet to be sufficiently far from the sensor. In contrast, with AMR sensors, designers can incorporate not only the detection direction but also a magnetic-field direction that facilitates switching to the OFF state. This makes it easier to design reliable ON/OFF detection tailored to the application, even in structures with nearby magnets or in devices where magnets must be placed in limited space.
In particular, applications such as cylinder position detection, meter rotation detection, and open/close detection for electronic locks and security devices require reliable ON/OFF detection even when magnets must be placed in limited space. Because the magnetic-field direction that facilitates switching to the OFF state can be incorporated into the design, AMR sensors help enable reliable detection tailored to the application.
Murata's AMR sensors are magnetic switches that integrate a sensor based on an AMR element—whose resistance changes with magnetic-field strength and direction—and an ASIC on a single chip. ASIC stands for application-specific integrated circuit, an integrated circuit designed specifically for a particular application. By integrating an ASIC optimized for the target application and product, the overall circuit can be simplified, helping reduce power consumption and size. The ASIC in an AMR sensor is a dedicated circuit that quickly converts small magnetic-field changes detected by the sensing element into digital signals and sends them to external devices such as microcontrollers. This integration of the AMR element and ASIC enables compact, high-performance, low-power magnetic sensors.
By improving the overall circuitry within its AMR sensors, Murata offers products that combine low-voltage operation with low current consumption. This helps reduce battery drain in standby mode and extend operating time in healthcare and wearable devices powered by small coin-cell batteries.
Magnetic switches are widely used for position detection in cylinders and sliding windows; rotation detection in gas, water, and electricity meters and automatic locking systems; open/close detection in laptops, tablets, and refrigerators; and omnidirectional detection of magnetic fields over a wide range of directions. We offer products suited to each application. Our lineup covers a range of sensitivity and response characteristics, including high-speed-response models, high-voltage-compatible models, and models specialized for rotation detection.