TLI5012BE1000_15 Datasheet, PDF (11/37 Pages) Infineon Technologies AG – GMR-Based Angle Sensor

TLI5012B E1000
Functional Description
can be configured via SSC interface to use an external clock signal supplied on the IFC pin as source for the PLL,
instead of the internal clock. External clock mode is only available in PWM or SPC interface configuration.
2.2.3 SD-ADC
The Sigma-Delta Analog-Digital-Converters (SD-ADC) transform the analog GMR voltages and temperature
voltage into the digital domain.
2.2.4 Digital Signal Processing Unit
The Digital Signal Processing Unit (DSPU) contains the:
• Intelligent State Machine (ISM), which does error compensation of offset, offset temperature drift, amplitude
synchronicity and orthogonality of the raw signals from the GMR bridges, and performs additional features
such as auto-calibration, prediction and angle speed calculation
• COordinate Rotation DIgital Computer (CORDIC), which contains the trigonometric function for angle
calculation
• Capture Compare Unit (CCU), which is used to generate the PWM and SPC signals
• Random Access Memory (RAM), which contains the configuration registers
• Laser Fuses, which contain the calibration parameters for the error-compensation and the IC default
configuration, which is loaded into the RAM at startup
2.2.5 Interfaces
Bi-directional communication with the TLI5012B E1000 is enabled by a three-wire SSC interface. In parallel to the
SSC interface, an Incremental Interface (IIF) can be selected, which is available on the IFA, IFB, IFC pins.
2.3
Sensing Principle
The Giant Magneto Resistance (GMR) sensor is implemented using vertical integration. This means that the
GMR-sensitive areas are integrated above the logic part of the TLI5012B E1000 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)
With this full-bridge structure the maximum GMR signal is available and temperature effects cancel out each other.
In Figure 2-2, 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 ARCTAN2, the true 360° angle value is calculated out of the raw X and Y signals
from the sensor bridges.
Data Sheet
11
Rev. 1.1, 2015-09