TLE5012_10 Datasheet, PDF (10/64 Pages) Infineon Technologies AG – GMR-Based Angular Sensor for Rotor-Position Sensing

2
Functional Description
TLE5012
Functional Description
2.1
General
The GMR sensor uses vertical integration. This means that the GMR-sensitive areas are integrated above the
logic portion of the TLE5012 device. These GMR elements change their resistance depending on the direction of
the magnetic field.
Four individual GMR elements are connected to one Wheatstone sensor bridge. These GMR elements sense one
of two components of the applied magnetic field:
• X component, V_x (cosine) or the
• Y component, V_y (sine)
The advantage of a full-bridge structure is that the amplitude of the GMR signal is doubled and temperature effects
cancel out each other.
GMR Resistors
V_X
0°
S
V_Y
N
ADC_X+ ADC_X-
GND
ADC_Y+ ADC_Y-
V_DD
90°
Figure 1 Sensitive bridges of the GMR sensor
Note: In Figure 1, the arrows in the resistors represent the magnetic direction which is fixed in the Reference
Layer. If the external magnetic field is parallel to the direction of the Reference Layer, the resistance is
minimal. If they are anti-parallel, resistance is maximal.
The output signal of each bridge is only unambiguous over 180° between two maxima. Therefore two bridges are
oriented orthogonally to each other to measure 360°.
With the trigonometric function ARCTAN, the true 360° angle value can be calculated, based on the relationship
of X and Y signals.
Because only the relative values influence the result, the absolute magnitude of the two signals is of minor
importance. Therefore, it is possible to compensate for most external influences on the amplitudes.
Final Data Sheet
10
V 1.0, 2010-11