At Sensors Expo 2018, Evgeny Burmistrov, an engineering manager from Crocus Technology discusses the company’s tunnel magnetoresistance (TMR) magnetic sensor technology. For sensing, TMR is used in number of different applications.

Crocus is advancing its TMR capabilities toward linear and 2D sensing. Burmistrov shows the response of a TMR sensor measuring the speed of a rotating disc that is displayed as sine and cosine waveforms. The two linear sensors sense in the orthogonal directions. The combination of these two voltages provides the precise angle of the magnetic field source. Stopping or slowing down the motion of the disc to simple hand operation provides a dramatic example of how close the sensor follows the magnetic field vectors – even at very slow speeds.

Using the company’s patented Magnetic Logic Unit™ (MLU™) approach, TMR technology provides ultra-sensitive magnetic sensors with the highest sensitivity, the lowest power consumption, and smallest size by comparison to the other established and more well-known magnetic technologies such as Hall effect, anisotropic magnetoresistance (AMR), and giant magnetoresistance (GMR).

Offered in a small QFN package, the TMR angular sensor delivers contactless angle measurements up to 360° over a wide temperature range of -40° to 125°C. This makes the sensor suitable for a wide range of applications including convertible laptops, robotics, smart home controls, white goods, motor motion controls and more.

The TMR technology is also used for digital latches, contactless field sensing and digital rotation/speed sensing. With differential programming capabilities, the sensors operate at MHz range frequencies and offer high reliability for applications in harsh environments.