Texas Instruments TMAG5328, User Manual, Page: 5 / 36

4 Hardware
Figure 4-1 shows a schematic snippet of the TMAG5328 portion of the TMAG5328EVM. The EVM supports
adjusting B
OP
with three on-board options: a GUI-controlled DAC, a potentiometer, or a fixed resistor. The
different B
OP
options are selected based on the configuration of resistor R7 and header J3 in Figure 4-1 . The
EVM also has other headers and test points for further configuring the EVM.
Figure 4-1. Schematic Snippet of TMAG5328 Portion of TMAG5328EVM
4.1 EVM Threshold Adjustment Options
4.1.1 Adjusting Threshold With DAC
One option for setting the B
OP
of the TMAG5328 is to use the onboard DAC43701 DAC to output a voltage
on the TMAG5328 ADJ pin. The DAC43701 is an 8-bit voltage-output DAC with nonvolatile memory and I
2
C
interface. The nonvolatile memory retains the set values in the absence of a power supply. As a result, if the
DAC output settings are stored in the nonvolatile memory of the DAC, a microcontroller does not need to
reconfigure the DAC after each reset. The DAC43701 can set the B
OP
of the TMAG5328 without using the SCB
afterward if the desired DAC output voltage was previously stored in the nonvolatile memory of the device. The
SCB and GUI will only be needed for the initial programming of the DAC voltage and the storing of this voltage
into nonvolatile memory.
The DAC43701 also has an internal reference option feature that is used in the TMAG5328EVM. By using the
internal reference, the output voltage of the DAC would not change drastically across power supply voltage as
long as the power supply voltage for the DAC43701 is anywhere within the recommended 1.8-V to 5.5-V range.
Use Equation 1 to translate the voltage on the ADJ pin into the B
OP
setting:
B
OP
= 0.0125 × ADJ
voltage
(1)
where:
• B
OP
is in units of mT
• ADJ
voltage
is in units of mV
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TMAG5328 Evaluation Module 5
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