TLE5012 Datasheet, PDF (9/57 Pages) Infineon Technologies AG – GMR-Based Angular Sensor for Rotor Position Sensing

2
Functional Description
TLE5012
Functional Description
2.1
General
The GMR sensor is implemented using 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
90°
V_X
0°
S
V_Y
N
ADCX+ ADCX-
GND
ADCY+ ADCY-
VDD
Figure 1 Sensitive Bridges of the GMR Sensor
Note: In Figure 1, the arrows in the resistors symbolize the direction of the Reference Layer, which is used for the
further explanation.
The output signal of each bridge is only unambiguous over 180° between two maxima. Therefore two bridges are
orientated orthogonally to each other to measure 360°.
With the trigonometric function ARCTAN, the true 360° angle value can be calulated which is represented by the
relation of X and Y signals.
Because only the relative values influence the result, the absolute size of the two signals is of minor importance.
Therefore, most influences to the amplitudes are compensated.
Target Data Sheet
9
V 0.46, 2009-09