Tunneling Magnetoresistance (TMR) Technology

Allegro’s XtremeSense™ TMR technology (Tunnel Magnetoresistance) provides the highest magnetic sensitivity, the lowest power consumption, and the smallest size by comparison to other magnetic technologies such as Hall, AMR, and GMR. Accelerating various applications from renewable energy systems, xEV, and connected consumer devices, Allegro’s XtremeSense TMR technology enables current and position sensors to achieve industry-leading performance figures and cost levels.

Efficient Power Conversion

Accurately measures the full dynamic range and provides a cleaner signal.

Adoption of Wide Bandgap Transistors

Wide bandgap transistors such as GAN and SiC require high bandwidth current sensors which XtremeSense TMR achieves without sacrificing accuracy and resolution.

Reduce The Energy Footprint

Delivers the lowest power consumption in any magnetic sensing product category.

TMR is an ideal fit for high growth industries such as automotive, industrial and consumer goods that require higher accuracy, greater bandwidth and lower power consumption.

At the heart of XtremeSense TMR technology is a thin-film magneto-resistive device, which is called a “Magnetic Tunnel Junction” (MTJ). In its simplest form, the MTJ consists of two electric-conducting magnetic layers on either side of a thin but highly robust insulating layer. One magnetic layer has a fixed magnetic moment direction, while the other can change freely to follow the direction of the local magnetic field.

For more information about the performance advantages of TMR versus other magnetic sensing technologies, please read our From Hall Effect to TMR application note.

Hall-Effect vs AMR vs GMR vs TMR Diagram 

XtremeSense TMR Technology Product Portfolio

Product Description
  CT110 High Linearity/High Resolution Contact Current Sensor
TMR Current Sensor with Ultra-Low Noise and <1% Total Error
TMR Current Sensor with Ultra-Low Noise and <0.7% Total Error
TMR Current Sensor with Ultra-Low Noise, <0.7% Total Error and Common-Mode Field Rejection in SOICW-16 Package
Product Description
  CT220 High Linearity, High-Resolution TMR Contactless Current Sensor in Miniature Form Factor
1 MHz Bandwidth Contactless Current Sensor
Product Description
Integrated Unipolar TMR Switch/Latch
  CT8122 Integrated Bipolar TMR Switch/Latch
Integrated Omnipolar TMR Switch/Latch
Product Description
Ominpolar TMR Analog Sensor with Dual Analog and Digital Output Operation Capability
  CT100 1D TMR Linear Sensor with Analog Differential Outputs
  CT310 2D TMR Angle Sensor with Sine/Cosine Outputs

Dive into the electric current flow that creates the TMR advanced sensor and makes TMR possible.

TMR Electrical Current Flow Diagram showing the Free Layer, Barrier Layer, and Fixed Layers

The relative magnetization direction of the Free Layer and the Reference Layer determines the resistance of the MTJ. A parallel magnetization direction achieves the lowest possible resistance level. The anti-parallel magnetization direction enables the highest possible resistance level.

TMR Resistance vs Current Diagram Image

This variation in electrical resistance is then immediately detected and amplified to accurately sense the local magnetic field. This feature creates the TMR advanced sensor with higher sensitivity, lower power consumption, and stable characteristics.

TMR Sensor vs. Hall Sensor Comparison Diagram

TMR sensors more accurately measure the full dynamic range. These sensors have excellent working dynamic range, with high linearity, low hysteresis, and high sensitivity characteristics (that is, the magneto-resistive response curve has a steep slope).

Documentation & Resources