SLYA093 September   2025 TMAG3001 , TMAG5253

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Benefits of Hall-Effect Sensors
    1. 2.1 Hall-Effect Sensors for Keys
    2. 2.2 3D Hall-Effect Sensors for Knobs
  6. 3Keypress Design Considerations
    1. 3.1 Simulating Keypress Design
    2. 3.2 Keypress Bench Results
  7. 4Keyboard Design Example
  8. 5Summary
  9. 6References

3.2 Keypress Bench Results

To verify the results simulated by TIMSS, a physical bench setup was created. For these tests, both a TMAG5253BA3 and a TMAG5253BA2 were populated onto a HALL-ADAPTER-EVM breakout board. This way the results from both variants can be compared to see if the TMAG5253BA3 variant is still the option, as seen in TIMSS. The lab setup consisted of the Samarium Cobalt YX18 magnet found in magnetic keyboard switches being placed in a fixed location. The HALL-ADAPTER-EVM with the TMAG5253BA2 was then placed such that the center of the magnet was lined up with the center of the magnet. To begin, the sensor was placed in the fully pressed state so that the magnet was approximately 2.1mm away from the sensor. The sensor was then moved in increments of 0.05mm until the sensor had moved a total of 4mm away from the starting position, placing the sensor 6.1mm away from the magnet, to mimic the magnetic keyboard switch going from pressed to unpressed. Figure 3-9 shows the data results collected from the sensor during this time.

TMAG5253BA2 Bench Results Figure 3-9 TMAG5253BA2 Bench Results

Similar to the results observed from the TIMSS simulation for the TMAG5253BA2 variant, the sensing element becomes saturated when the magnet is reaching the fully pressed state which means that no meaningful data can be extracted at this point. Figure 3-10 shows the results measured from the TMAG5253BA3. From the results shown in Figure 3-10, not only is there no saturation, but at each increment of 0.05mm, the sensor was able to observe incremental changes as the sensor was moved further away from the magnet.

TMAG5253BA3 Bench Results Figure 3-10 TMAG5253BA3 Bench Results

Something to keep in mind with the results observed from the above bench testing, as with all testing, is human error. While the bench setup was designed to be as accurate as possible, with a Newport linear motion controller being used to control the motion of the sensor, the sensor is not precisely aligned with the center of the magnet. Additionally, this is possible that the original position from the sensor to the magnet was not exactly 2.1mm, which can account for the slight differences seen in the bench test results when compared to the results observed from the simulation.