Why TMR Technology?

TMR technology represents a paradigm shift in magnetic sensing. Unlike traditional Hall-effect sensors, which rely on the deflection of charge carriers under the influence of an external magnetic field, TMR sensors exploit the phenomenon of tunneling magnetoresistance. This involves measuring the change in electrical resistance through a thin insulating layer sandwiched between two ferromagnetic layers, where the resistance is modulated by the external magnetic field. This fundamental difference translates into several key advantages for TMR sensors:

• Unparalleled Sensitivity: Sensors exhibit significantly higher sensitivity compared to Hall-effect sensors. This allows for the detection of minute magnetic field variations, enabling high-precision measurements.
• Enhanced Resolution: Increased sensitivity of TMR technology directly translates to superior resolution. This is crucial in applications demanding precise position or motion detection, such as automotive steering angle sensing or industrial automation.
• Customizable Linear Range: TMR sensors offer exceptional linearity and allow for tuning the linear range to optimize performance for specific applications. This flexibility enhances the signal-to-noise ratio (SNR) and ensures accurate, predictable output signals, which simplifies system calibration and improves overall accuracy.
• Low Noise Operation: TMR technology inherently exhibits lower noise levels compared to Hall-effect sensors. This is particularly beneficial in applications where signal integrity is paramount, such as current sensing in high-power systems.
• Low Power Consumption: TMR sensors are designed for ultra-low power operation, making them ideal for battery-powered and energy-constrained applications.

Key Performance Metrics: A Closer Look

To fully grasp the superiority of TMR sensors, let's delve into the specific performance metrics:

• Resolution: Boasts a resolution up to 8 times higher than comparable Hall-effect sensors at high rotational speed (40K rpm) and 20 times higher at high speed (5 Mhz). This means they can discern much smaller changes in magnetic fields, leading to finer control and more accurate measurements.
• Linearity: TNR sensors have a customizable range for optimal signal-to-noise ratio (SNR). This provides a highly predictable output proportional to the magnetic field and facilitates easier system calibration and enhanced accuracy, a benefit not achievable with Hall sensors.
• Hysteresis: Technology inherently exhibits minimal hysteresis, meaning the sensor output is minimally affected by the magnetic field's history. This ensures consistent and repeatable measurements.
• Cross-Axis Rejection: Sensors effectively reject interference from magnetic fields perpendicular to the sensing axis. This is crucial in applications where external magnetic fields could distort measurements.
• Power Consumption: TMR sensors achieve <1 uW level power consumption due to their low current operation and ability to function at low frequencies.

How TMR Achieves Best-in-Class Specifications

The exceptional performance of TMR sensors stems from a combination of factors:

• Advanced Materials: Proprietary TMR materials with optimized magnetic properties, leading to enhanced sensitivity and reduced noise.
• Innovative Sensor Design: The sensor architecture is meticulously designed to maximize sensitivity and minimize unwanted effects like hysteresis and cross-axis sensitivity.
• Robust Fabrication Process: A state-of-the-art fabrication process ensures high sensor-to-sensor uniformity and reliability, even in demanding operating conditions.

Conclusion

TMR technology represents a significant leap forward in magnetic sensing. Its superior sensitivity, resolution, linearity, and low noise operation make it ideal for a wide range of applications, from automotive and industrial automation to consumer electronics and beyond. As the demand for more precise, efficient, and reliable sensing solutions continues to grow, TMR is poised to become the new gold standard in magnetic sensing.

Allegro MicroSystems’ XtremeSense TMR technology provides the highest magnetic sensitivity, the lowest power consumption, and the smallest size by comparison to other magnetic technologies.  For more details, take a look at our recent whitepaper.