Magnetic switches often sit quietly inside devices, detecting movement or alignment without drawing much attention. What they do draw is power, and for engineers designing products that never switch off, smart meters, wearables, and connected sensors, that power cost adds up. Littelfuse has released two new Tunnelling Magnetoresistance (TMR) switches designed to cut that overhead while improving reliability: the LF21112TMR and LF11215TMR.
Smarter Sensing, Lower Current
Both devices use TMR technology combined with a low-power CMOS design. It’s a pairing that delivers higher magnetic sensitivity than a standard Hall-effect sensor while consuming a fraction of the energy. The LF21112TMR detects both magnetic poles, making it flexible in compact designs where magnet alignment can’t always be controlled. Typical current draw is just 200 nA, a level that allows the switch to run continuously on minimal battery power.
The LF11215TMR focuses on directional detection. It responds to one polarity and resets with the opposite, providing precise switching for rotational or position-based systems. With 1.5 µA of current draw and sensitivity around 17 Gauss, it suits equipment that needs fast, accurate readings without constant calibration.
Practical Design and Real-World Use
Each device comes in a small SOT23-3 package and operates from 1.8 to 5.0 volts. Schmitt trigger inputs help filter noise, while a push-pull CMOS output ensures stable digital signals. In practice, engineers can drop either switch into existing Hall-effect layouts without major redesigns, giving older products a path to lower power consumption.
Applications range from tamper detection in smart meters to lid sensing in appliances and low-power motion tracking in robotics. Their resistance to magnetic interference and strong thermal stability make them dependable in industrial and home environments alike.
With these TMR switches, Littelfuse is giving designers new tools to extend battery life and simplify sensing. The result is smaller, smarter, and more efficient products built for a connected world.
Learn more and read the original announcement at www.littelfuse.com
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