TLE5009-E2000 Datasheet, PDF (8/32 Pages) Infineon Technologies AG – GMR-Based Angular Sensor

2
Functional Description
TLE5009
Functional Description
2.1
General
The GMR sensor is implemented using vertical integration. This means that the GMR sensitive areas are
integrated above the analog portion of the TLE5009 chip. These GMR elements change their resistance
depending on the direction of the magnetic field.
Four individual GMR elements are connected in a Wheatstone bridge arrangement. Each GMR element senses
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.
GMR Resistors
V_X
0°
S
V_Y
N
ADCX+ ADCX-
GND
ADCY+ ADCY-
VDD
90°
Figure 1 Sensitive bridges of the GMR sensor
Note: In Figure 1, the arrows in the resistors symbolize the direction of the reference layer. Size of the sensitive
areas is greatly exagerated for better visualisation.
The output signal of each bridge is unambiguous in a range of 180°. Therefore two bridges are oriented
orthogonally to each other to measure 360°.
With the trigonometric function ARCTAN, the true 360° angle value that is represented by the relation of X and Y
signals can be calculated according to Equation (1).
(1)
Data Sheet
8
Rev. 1.1, 2012-04