Bosch Sensortec GmbHBMM350Magnetwiderstandssensor

Considering the increasing demands for compact, energy-efficient and highly precise sensing in consumer electronics, wearables, mobility and industrial systems, traditional magnetometer technologies are hitting their limits. Hall effect, AMR and GMR sensors—while proven—struggle to meet the sensitivity, noise, and power requirements of emerging applications.In this article from Bosch, learn how Tunnel Magnetoresistance (TMR) technology, found in the BMM350 3-axis magnetometer, delivers high sensitivity and low noise to position sensing applications.

Tunnel Magnetoresistance (TMR) has now emerged as a breakthrough solution. Based on magnetic tunnel junction (MTJ) architecture, TMR sensors achieve magnetoresistance (MR) effects >100%—an order of magnitude higher than AMR or GMR. This results in extremely high sensitivity, ultra-low noise, and current consumption as low as 200 µA @ 100 Hz. Thanks to their spin-dependent tunneling mechanism, TMR sensors also exhibit binary-like output behavior, enabling precise signal detection in digital environments.

Core benefits of TMR sensors:

• •  Outstanding sensitivity and linearity over wide magnetic field ranges
• •  Minimal power draw for always-on, battery-driven designs
• •  High robustness against temperature variation and magnetic shock
• •  360° sensing capability in compact packages

TMR-based sensors are already enabling accurate orientation tracking in AR/VR, improved navigation and current sensing in mobility systems, and robust position and angle detection in industrial automation. Their low noise floor even allows measurement of ultra-weak magnetic fields in medical or geophysical use cases.

The Bosch Sensortec BMM350: TMR in action

As a 3-axis magnetometer built on TMR technology, the BMM350 exemplifies best-in-class performance:

• •  200 µA current consumption (100 Hz ODR)
• •  >70% lower noise vs. standard Hall sensors (x/y axis)
• •  100x higher sensitivity than AMR or Hall
• •  WLCSP package: 1.28 × 1.28 × 0.5 mm

A patented “field shock recovery” feature ensures reliable performance even when exposed to magnetic interference from components like smartphone speakers.

Applications include head-tracking in hearables and AR headsets, orientation and motion detection in smartphones and tablets, speed sensing in e-bikes, and precise current monitoring in battery-powered systems.

Outlook

TMR is not just a technological improvement—it’s a foundation for future-ready sensing. As devices become smarter and more context-aware, TMR’s efficiency, precision and integrability position it as the go-to magnetic sensing technology for next-gen applications.

Distributors: TMR technology—powered by Bosch Sensortec’s BMM350—enables your customers to design for tomorrow, today.