SLYA060 August   2022 TMAG5110 , TMAG5110-Q1 , TMAG5111 , TMAG5111-Q1

 

  1.   Abstract
  2.   Trademarks
  3. Introduction
  4. System Block Diagram
  5. Key System Specifications
  6. HW Connections
  7. Software
    1. 5.1 TI-RSLK LaunchPad Software
    2. 5.2 LaunchPad Software
  8. How to Design With Hall-Effect Latches
  9. Simulation Results
    1. 7.1 Select Device Sensitivity
    2. 7.2 Select Axis of Sensitivity
  10. Performance Comparison
    1. 8.1 Speed and Direction
    2. 8.2 Power Consumption
    3. 8.3 Susceptibility to External Particles
  11. Encoder Board Schematic and Image
  12. 10Summary

Select Axis of Sensitivity

In rotary encoding systems that require both speed and direction, the sensors should be placed ideally 90° out of phase from each other. Using a 2D sensor enables the user to achieve this 90° offset more simply because the sensors are naturally orthogonal to each other, meaning there is a natural 90° phase difference from each sensor. This means that, when picking a 2D sensor, it is necessary to pick the two directions that have the closest phase angle difference of 90° from each other. To calculate this, we can use the following formula:

Equation 2. θ°=x2-x1period×360°

Where X2- X1 is the difference between the leading and lagging sinusoidal waveforms. This difference is converted to a fraction by dividing it by the entire period of the signals.

The fraction multiplied by 360° will provide the phase difference between the two sinusoidal waveforms. On the encoder board that was created, due to the rotation of the sensor (board image in Figure 9-2), a 65.45° offset was estimated from the simulation. The phase angle calculation is below.

Equation 3. 65.45°=25-1933×360°
With ideal Hall sensor placement, meaning a 90° angle is achieved, the signal should yield a 50% duty cycle on the output. When the offset is greater or lesser than 90°, it may lead to uneven periods in the duty cycle, as seen for this system in Figure 8-6.