Analog Devices’ ADMT4000

There are many single-turn 360° absolute position sensors on the market today, but the ADMT4000 is the first single chip sensor brought to market with an absolute measurement range of > 360°. The sensor IC incorporates a GMR based spiral multiturn sensor, an AMR angle sensor, a signal conditioning IC and has a 46-turn measurement range providing an absolute 0° to 16,560° digital output.

The sensor is non-contacting and has the unique ability to measure and track multiple turns of a rotating magnetic field in the absence of electrical power. The operating principle of the sensor is based on Shape Anisotropy, the generation of domain walls in the presence of an external magnetic field. As the external magnetic field rotates, the domain walls propagate through narrow spiral tracks (nanowires) changing the state of each spiral leg element. The spiral elements are fabricated on a Giant Magneto Resistance (GMR) process and the state change is essentially a change in the resistance in the presence of a rotating magnetic field. The multiturn sensor tracks the movement of the rotating magnetic field without electrical power and when power is reapplied, the signal conditioning IC reads back the state (resistance) of the GMR spiral legs and determines the new turn count state. The multiturn sensor is accurate to a quarter turn (90°) and the ASIC combines the multiturn position with precise angle information from the AMR angle sensor to provide the 0° to 16,560° absolute digital output and is accurate to +/-0.25° over the complete measurement range.

Analog Devices Inc. (ADI), having already developed angle sensors based on AMR technology, recognised a void in the market for silicon based multiturn position sensors and decided to bring this innovative multiturn technology to the market.

The development of this new technology and the first multiturn position sensor (ADMT4000) has taken many years of advanced research and development at the Analog Devices European Research and Development Centre (ERDC) and Magnetic Sensor process development facilities in Limerick, Ireland. There have been many challenges along the way in getting this new multiturn technology ready for high volume production in Industrial and Automotive applications. Finally, these challenges have been overcome and the technology is now ready to go to volume production and is set to revolutionise the position sensing markets and will be on display at electronica 2024.

Find out more: https://www.analog.com/en/products/admt4000.html#part-details