MLX90333
Triaxis 3D-Joystick Position Sensor
In summary, along X-axis, the left Hall plate measures “BX⊥ - BZ” while the right Hall plate measures “-BX⊥
- BZ”. Similarly, along the Y-axis, the left Hall plate measures “BY⊥ - BZ” while the right Hall plate measures
“-BY⊥ - BZ”.
Through an appropriate signal processing, the Tria⊗is™ sensor front-end reports the three (3)
components of the applied magnetic flux density B i.e. BX, BY and BZ.
Indeed, by subtracting the signals from the two (2) Hall plates in each pair, the components BX⊥ and BY⊥
are measured while BZ is cancelled. To the contrary, by adding the signals from the two (2) Hall plates in
each pair, the component BZ is measured while BX⊥ and BY⊥ are cancelled
In a joystick based on a “gimbal” mechanism as shown on Figure 3 (left), the magnet (axial magnetization)
moves on a hemisphere centered at the IC. The flux density is described through the following
relationships:
BX = SIN (α ) ⋅ COS(β )
BY = COS(α ) ⋅ SIN (β )
BZ = COS(α ) ⋅ COS(β )
Those components are plotted on the Figure 5, Figure 6 and Figure 7.
Figure 5 – Magnetic Flux Density – BX, BY, BZ
3901090333
Rev. Preliminary
Page 8 of 38
Data Sheet
May 07