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Home » NEWEST Products » New by Manufacturer » Murata » Murata AMR Magnetic Switch Sensors
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Murata AMR Sensors (Magnetic Switches)


AMR Sensors (Magnetic Switches)

Exploiting the magnetoresistive effect, AMR sensors have an IC to detect changes in the magnetic resistance of a magnetoresistive element affected by an external magnetic field. Many magnetic switches are used for cylinder position detection, smart meter, and the open/close detection for equipment such as single-lens reflex cameras, video cameras, and refrigerators. You can choose the best products from our broad lineup of AMR sensors with different package sizes and sensitivity ranges.


Position/Rotation Detection

This series of versatile sensors can detect a broad range of magnetic movements. Position sensing and rotation detection represent two major applications. The great diversity offers customers a choice of AMR sensors ideal for the conditions of their environment of use (movement to be sensed, supply voltages, temperatures, and response frequency, etc.).


Rotation Detection

Specialized for detecting rotations, this series of AMR sensors features stable output characteristics, making them ideal for the precise detection of rotational displacements. Using 2 AMR rotational sensors enables the sensing of the rotational direction. Products that consume extremely low currents, for example the MRUS74X, are also available, making the scope of applications even broader.


Applications

AMR sensor is one of the best fit for its usage such as non-contact switches for mobile devices.

  • Open/Close detection
    • For Mobile phones, Notebook PCs, Digital cameras and more…
    • For Refrigerators, Washing machines and other Home appliances
    • For Security equipments for doors/windows
  • Rotation detection
    • Smart gas meter
    • Smart water meter etc.

AMR Sensor Features of MRMS Series


Difference from Hall IC

Murata AMR Sensor Difference from Hall IC
  • AMR sensor detects a horizontal magnetic field which gives you Design Flexibility allowing a single magnet to support multiple sensing positions in terms of mounting locations.
  • By this feature, AMR sensor has a merit to be used even for the space conscious applications.

Murata AMR Sensor Relation between sensor and magnetic field

Relation between sensor and magnetic field

Difference from a Reed Switch

AMR Sensor has the following features compared with a reed switch.

  • Small in size and relatively inexpensive in price
  • Strong shock-tolerant and vibration-tolerant; which leads to high reliability
  • Longer life expectancy thanks to its Contact-less feature

Murata AMR Sensor Difference from a reed switch



Fundamental principles


Basic Characteristics

AMR sensor is a product which utilized the magnetic thin films such as nickel and iron.
MR element made of Ni-Fe called perm alloy is formatted on wiring layer of the semiconductor IC.
When the external magnetic field is applied to MR element, the resistant rate of MR element will change.
Then voltage difference occurs.

Murata AMR Sensor Operation Image
Operation Image

Block Diagram

  • AMR sensor consists of bridge circuits (which consists of 4 MR resistances)
  • 4 MR resistances are divided into 2 groups, and it is arranged so that each may become perpendicular
  • MR element has unique characteristics that the resistance rate drops when the external magnetic field is applied perpendicularly to the current. When the resistance rate drops, the neutral voltage point of the bridge circuit will change. This change is input as analog voltage signal into the IC.
  • IC built-in amplification circuit inside judges automatically whether the input analog is higher or lower than the threshold voltage. Then ON/OFF digital output is performed.

Murata AMR Sensor Block Diagram

Chattering Prevention

  • Magnetic field has hysteresis to prevent chattering. (Chattering is a phenomenon in which an electric signal repeats intermittence by detailed and very quick mechanical vibration, when the point of contact of a relay or a switch changes.)
  • When the magnet approach to the sensor and the magnetic flux density exceeds MOP, VOUT changes from H to L.
  • MR element has unique characteristics that the resistance rate drops when the external magnetic field is applied perpendicularly to the current. When the resistance rate drops, the neutral voltage point of the bridge circuit will change. This change is input as analog voltage signal into the IC.
  • When the magnet leaves and the magnetic flux density decreases below MRP, VOUT changes from L to H.

Murata AMR Sensor Chattering Prevention




  • Murata Electronics
  • Industrial
  • Electromechanical|Switches|Sensors