Accurate 3D Measurement of Magnetic Fields for Automotive Gear Selector : Page 4 of 6

October 10, 2016 //By Hannes Birk and Sigmund Zaruba, Infineon Technologies
Accurate 3D Measurement of Magnetic Fields for Automotive Gear Selector
The TLE493D-W1B6 magnetic sensor provides accurate three-dimensional (3D) magnetic field measurement, extremely low energy consumption and integrated magnetic field alert functionality. Potential automotive applications for this technology are gear selectors, control elements, top column modules and applications involving linear movements or angle measurement.
be performed. This mode is particularly suited to applications for which very fast magnetic movements must be detected. The sensor’s power consumption is, at most, 3.7 mA at a sampling rate of about 8 kHz, corresponding to 8,000 measurement cycles/second.

A total of eight different “low power” modes have been implemented in the TLE493D-W1B6. In all of these modes, the sensor regularly and autonomously wakes up out of power down mode in order to perform magnetic measurements. The power consumption depends on the number of measurement cycles/second (see Figure 3).

 

In “master-controlled” mode, the sensor can be flexibly read out according to the requirements of the application. After each measurement, the sensor waits until the microcontroller (master) has read out the register. Depending on the application conditions, the read-out process can be performed immediately or with a slight delay. As soon as the microcontroller has detected the magnetic values, a new sensor measurement cycle is triggered. This mode is particularly useful when several TLE493D-W1B6 sensors are connected through an I²C bus for the detection of large linear movements. The microcontroller decides which sensor’s data is most relevant and triggers the corresponding sensor.

 

Application: Gear Selector in a Mid-Range Car

 

A magnetic 3D sensor is very useful in detecting the position of the gear selector in an automobile as the existing ‘state-of-the-art’ solution, which uses at least six Hall switches, can be replaced by a single 3D sensor. Because the TLE493D-W1B6 has the same case dimensions as modern Hall switches, a great deal of space, as well as money, can be saved.

Using a gear selector for a current mid-range car as an example, here we will evaluate how the 3D sensor provides an alternative to the current solution.

Figure 4 (left) shows six gear selector positions on a circular arc at intervals of about 6 °. The original gear selector is detected by means of a Hall

Design category: 

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