Texas Instruments HEADON-MAG-ACC Magnetic Sensing Attachment

The first portion of the Texas Instruments HEADON-MAG-ACC is the screw, which has a thread with a 3mm pitch. The bottom base of the screw has an opening where an N52-grade cylindrical magnet is placed, thereby causing a magnetic field in the Z direction that the Hall position sensor can sense. When the screw is fully unfastened at the top of the base, the distance from the attachment to the top of the Hall position sensor’s package is approximately 16.5mm. The threading on the screw has a length of 12.7mm. As a result, the linear displacement from when the screw is fully unscrewed at the top of the base to when it is fully screwed into the base is approximately 12.7mm. In addition, the distance from the top of the Hall sensor package to the magnet is approximately 3.8 mm when the screw is fully fastened.

The second portion of the attachment is the base. The screw part of the attachment gets fastened into the top portion of the base, which is directly above the Hall position sensor. The screw can be rotated by hand or by using a flathead screwdriver on the slot at the top of the screw. Turning the screw clockwise when it is within the base causes the magnet to decrease its distance with respect to the Hall sensor, thereby increasing the magnetic flux density sensed by the Hall position sensor. The screw should be rotated counterclockwise to increase the distance from the Hall position sensor to the magnet embedded within the screw to decrease the magnetic flux density seen by the sensor. The linear distance from the magnet to the Hall sensor can be calculated using the sensed magnetic flux density and information on the characteristics of the magnet.