SBAU376A December   2021  – March 2022 TMAG5328

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Overview
    1. 1.1 Features
  5. 2Kit Contents
  6. 3Related Documentation From Texas Instruments
  7. 4Hardware
    1. 4.1 EVM Threshold Adjustment Options
      1. 4.1.1 Adjusting Threshold With DAC
      2. 4.1.2 Adjusting Threshold With Potentiometer
        1. 4.1.2.1 Using the Potentiometer to Estimate the Magnetic Flux Density Sensed by the TMAG5328
      3. 4.1.3 Adjusting Threshold With Fixed Resistor
    2. 4.2 Power Supply Options and Jumper Settings
  8. 5EVM Operation
    1. 5.1 Evaluation With SCB and GUI
      1. 5.1.1 Driver Installation
      2. 5.1.2 Firmware
        1. 5.1.2.1 Updating Firmware on SCB
      3. 5.1.3 GUI Setup and Usage
        1. 5.1.3.1 Initial Setup
        2. 5.1.3.2 GUI Operation
          1. 5.1.3.2.1 GUI Results Page
          2. 5.1.3.2.2 GUI DAC Configuration Page
      4. 5.1.4 Direct EVM Serial Communication
    2. 5.2 Evaluation Without SCB and GUI (EVM Stand-Alone Mode)
    3. 5.3 Head-On Linear Displacement Demo
  9. 6Schematics, PCB Layout, and Bill of Materials
    1. 6.1 Schematics
    2. 6.2 PCB Layout
    3. 6.3 Bill of Materials
  10. 7Revision History

4.1.2.1 Using the Potentiometer to Estimate the Magnetic Flux Density Sensed by the TMAG5328

Similar to sweeping the DAC output voltage to find the sensed magnetic flux density, an estimate of the sensed magnetic flux density can also be found by sweeping the potentiometer resistance by adjusting the position. In this approach, the potentiometer is placed to create the maximum resistance (Figure 4-5). If the output of the TMAG5328 is not asserted high (LED is OFF) for this potentiometer position, then replace R2 with a 5kΩ resistor. If the output is still not asserted high after replacing R2, then the sensed magnetic flux density is greater than the 15mT maximum magnetic flux density that can be sensed by the TMAG5328.

If the output of the TMAG5328 does in fact get asserted high when the maximum resistance is applied to the ADJ pin, then slowly turn the potentiometer clockwise until the output of the TMAG5328 first gets asserted low (LED is ON). As soon as the output gets asserted low, stop turning the potentiometer. The resistance between the ADJ pin and GND pin can then be measured and entered into the equation above to determine the TMAG5328's sensed magnetic flux density. If the potentiometer has been fully turned clockwise (Figure 4-4) and the output still does not get asserted low, replace R2 with a 2kΩ resistor. If the output is still not asserted low after replacing R2, then the sensed magnetic flux density is less than the 2mT minimum magnetic flux density that is able to be sensed by the TMAG5328.

Since the potentiometer is not affected by power resets, the potentiometer make sure that the same BOP is used after a power reset, assuming that the position is not moved. As a result, the potentiometer option can be used regardless if the SCB board is connected or not. If the position of the potentiometer is accidentally changed, however, then BOP changes. To make sure that the BOP does not change, one option is to measure the resistance between the ADJ pin and GND pin and then use this resistor with the Section 4.1.3. When making these resistance measurements, make sure to do the resistance measurement when the system is not powered.