The IoT Library: Intelligent Hall-Effect Sensors Open New Application Doors

In the age of ultra-low power, the sub-microamp, intelligent, Hall-Effect sensor may be the smartest sensor around.

Magnetic field sensors lie passively inside electronic systems, on constant alert, making them ideal motion detectors, especially in automotive and consumer applications.

But passive should not imply that magnetic sensors are dumb or idle devices. Not by any means. In the age of ultra-low power, the, sub-microamp, intelligent, Hall-Effect sensor may be the smartest sensor around.

Experimental Verification of Hall Effect Sensor Properties

Compared to an always-active sensor system, an intelligent Hall-Effect sensor system can be designed with its current consumption reduced from milliamps to less than a microamp — a reduction of over 1000x. The device’s extremely low power consumption enables the design and development of things like physical presence detection applications for door or window security systems. Here, a system can be directly powered by a single, low-cost coin-size battery cell over extended periods of unattended, continuous operation.

Just in case you missed the class on Hall and his eponymous effect:

In 1879 E. H. Hall observed that when an electrical current passes through a sample placed in a magnetic field, a potential proportional to the current and the magnetic field is developed across the material in a direction perpendicular to both the current and to the magnetic field. The Hall Effect is the basis of many practical electronics devices, including flow meters and other magnetic field measurement devices that detect and measure position, level, speed, motion, etc.

Hall Effect physics can also be used for detecting and sensing unique material and electrical characteristics. As noted in a recent research paper, “Hall Effect measurements continue to be a useful technique for characterizing the electrical transport properties of metals and semiconductors. ”To better understand sensor systems and the electronic properties of materials, study the Hall Effect.

To learn how designers balance hardware and firmware in Hall Effect sensor systems read Sub-Microamp, Intelligent Hall-Effect Sensing Delivers 20-Year Battery Life, by Mark E. Buccini, Product and Marketing Strategy, Motor Drive Business Unit, Texas Instruments. It’s an excellent guide to sensor system design issues like ultra-low-power standby modes, sensor duty cycles, and system power analysis.

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IoT Library

A word about this column: If you're like most engineers, you are forever on the lookout for fresh ideas and smart solutions. You have or are building your library of technical papers, documents, data sheets, products, technologies, standards, and applications for future and handy reference.

My goal here, and in future columns, is to explore some of the day’s greatest IoT design challenges—such as low power micro-computing, signal conditioning, wireless communications, sensors, actuator control, more efficient power sources and the man-machine interface—and pass along some useful resources. I hope you will find them valuable enough to archive or share.

Most important: It would be great if we could collaborate. Send me (richardkwallace@gmail.com) relevant knowledge resources that you may have found so that we can compile them for easy access.

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--Richard Wallace is a former editor in chief of EE Times. He has followed and reported on electronics, technology and design for 40 years, most recently as an independent journalist, online. You can reach him at richardkwallace@gmail.com.