Texas Instruments has introduced TMAG5170, the first device in a new family of 3D Hall-effect position sensors for real-time control in factory automation and motor-drive applications. The sensor is promoted as providing integrated functions and diagnostics to maximize design flexibility and system safety while saving energy.
Magnetic sensors, including Hall-effect sensors and other technologies, have design benefits and drawbacks. One constraint is the trade-off between obtaining extremely high accuracy and 3D device throughput. Stable sensors, for example, do not wander in response to changes in temperature, ambient conditions or even magnetic fields. It is usually simple to enhance one of the two ways, but not both.
TI said its TMAG5170 3D Hall-effect position sensor aims to enhance that relationship by offering high precision along with greater throughput. “This higher throughput has carry-over effects, such as much lower power operation when the full speed of the device isn’t required,” said Steven Loveless, TI’s marketing and applications manager for position sensing products.
Position sensing is virtually universal in high-performance automated systems that regulate motion, and position sensing technology directly affects system cost and performance. Sensor accuracy, speed, power and adaptability are among the factors considered when selecting the optimal position sensing system. Absolute position measurements using Hall-effect linear multi-axis position sensors should be exact, quick and dependable. The result is precise real-time control.
A key consideration when deploying a 3D Hall-effect sensor is that any magnet moving in free space surrounding the sensor must be easily recognized and monitored. The magnetic field surrounding a magnet’s pole is typically symmetrical, meaning that the identical input condition could be produced at numerous locations. In order to properly identify the absolute location, that feature requires careful design, ensuring that any change in magnetic flux density can be utilized to differentiate the magnet’s movement.
In smart factories, highly automated systems must function within an integrated manufacturing flow while simultaneously gathering data to regulate operations. In providing real-time control for higher efficiency and reduced downtime, automated equipment requires 3D position-sensing technology.
“Systems that utilize position or motion feedback in automation often are very dynamic in nature, and they must respond quickly and efficiently to varying changes in load, speed and other factors” Loveless said. The new TI sensor is designed to measure those dynamic conditions more precisely, “and help systems respond more quickly to those real-time changes,” he added.
TI said its TMAG5170 provides 2.6-percent full-scale total error at room temperature, with total error drift of just 3 percent, eliminating the need for end-of-line calibration and off-chip error compensation while also simplifying system design and manufacturing. The sensor supports measurements as high as 20 kSPS for low-latency throughput of high-speed mechanical motion.
It also eliminates the need for off-chip computation and enables variable sensor and magnet orientations by including features such as an angle calculation engine, measurement averaging as well as gain and offset correction. Regardless of sensor placement, TI said those characteristics simplify design and enhance system adaptability, allowing for quicker control loops, lower system latency and easier software development. The sensor’s integrated calculation capabilities also lower the system’s processing load by up to 25 percent, allowing engineers to reduce costs using general-purpose microcontrollers like TI’s low-power MSP430TM MCUs.
In the diagram below, the exact angular position of the motor shaft is monitored by the Hall-effect 3D linear position sensor, directly influencing system bandwidth and latency while evaluating feedback elements. The overall speed of the feedback loop can be enhanced by using a sensor capable of high-bandwidth readings, resulting in improved system performance.
Power consumption is a key consider when selecting a position sensor, including its battery or power management system. Sensors with low-power operating modes, such as wake-up, sleep and deep-sleep modes, are commonly used in battery-powered systems or platforms using a low-power source to optimize power consumption versus throughput. The TMAG5170’s various working modes and sampling rates, TI claimed, boost energy efficiency by up to 70 percent, allowing for optimal power usage throughout a 1- to 20-kHz sampling range for battery-powered devices or light-use modes when system efficiency is a key consideration.
Magnetic and mechanical designs also can benefit from using flexible 3D linear Hall-effect sensors with variable magnetic sensitivity levels and temperature correction options. Safety and improved diagnostics are becoming increasingly important in preventing equipment downtime and improved manufacturing quality as automated systems increasingly operate alongside humans. Hence, precision, speed, power and adaptability of position sensors and data they generate are key design considerations.