Magnetic angle sensor directly measures motor position

29th October 2014

Analog Devices

Siobhan O'Gorman

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Datasheet

Claimed to be the industry’s highest precision, highest speed magnetic angle sensor, the ADA4571 has been released by Analog Devices. According to the company, the device is four times more accurate (0.5° max), 60% faster and uses 40% less power than competing angle sensors. To reduce noise, optimise smoothness and torque performance, the sensor directly measures motor position.

This direct measurement enables designers of BDC motors to meet tighter environmental, noise and energy requirements. A custom, mixed-signal signal conditioning IC and sensing element based on anisotropic magneto-resistive (AMR) technology is integrated within the automotive qualified device.

Enabling high-accuracy readouts in harsh environments, the AMR and precision signal conditioning technology allow the ADA4571 to operate independently of magnet drifts due to lifetime, thermal influences or mechanical stress.

More effective commutation of the motor and better control of torque and speed performance, particularly in low RPM applications, is enabled by the high-accuracy position feedback information provided by the device. Allowing high-speed motor operation up to 50,000RPM, the sensor’s direct angle measurement principle reduces the effects of vibration and noise that can degrade motor performance. Efficiency is improved, emissions and heat lowered and operating life extended by the torque control. In high-dynamic applications such as industrial servo motors, robotics and electric power steering, the 2µs low-phase delay enables fast-closed-loop control and improves responsiveness.

The ADA5471, which includes a low-power sleep mode that expands application usage to remotely-powered systems, operates from a 2.7 to 5.5V range while consuming 6.5mA. Under high-magnetic-field conditions, the device sustains no damage and has negligible hysteresis. The need for calibration is removed by the sensor’s low temperature and lifetime-drift performance.

Direct, non-contact and wear-free angle measurement in a range of motor applications is provided by the ADA4571. Such applications include automotive systems such as electric power-assisted steering, braking, active suspension and stability control. For use in high-availability and safety-critical applications, the device supports advanced diagnostics.

Offered in a 8-lead SO package, the ADA4571 is priced at $1.98 each and sold in 10,000 unit quantities.