Texas Instruments TMAG5328, Руководство пользователя, Страница: 6 / 36

As an example, if 680 mV is applied to the ADJ pin, the B
OP
will be set to 8.5 mT.
The TMAG5328 ADJ pin can accept a voltage from 0.16 V to 1.2 V. To stay within this voltage range, the GUI
ensures that the DAC output voltage cannot be set outside of the 0.16-V to 1.2-V range.
The GUI allows setting the DAC voltage based on the following options:
• The magnetic flux density currently sensed by the TMAG5328 : For this option, the DAC determines the
sensed magnetic flux density by sweeping the voltage on the ADJ pin from 1.2 V (15 mT) to 0.16 V (2
mT) and then finding the first DAC code that causes the output of the TMAG5328 to assert low. This first
DAC code is converted back into the corresponding DAC output voltage and then the corresponding B
OP
using the equation above. If the TMAG5328 is asserted low after applying 1.2 V to the ADJ pin, the sensed
magnetic flux density is greater than the maximum 15-mT B
OP
supported by the device. If the TMAG5328 is
still asserted high even after applying 0.16 V to the ADJ pin, the sensed magnetic flux density is less than the
minimum 2-mT B
OP
supported by the device.
• Manually inputting one of the parameters below (the GUI only enables one of these parameters at a time):
– Desired B
OP
– Desired voltage on the ADJ pin
– ADJ equivalent resistance : This setting simulates applying a resistor on the ADJ pin by applying a
voltage that would create the same B
OP
as the input resistance.
The GUI also calculates an equivalent resistance value based on the DAC output voltage. The equivalent
resistance value is the resistance value for the
fixed-resistor threshold adjustment option that would generate the
same B
OP
as the currently set DAC output voltage. The equivalent resistance calculation allows the GUI to use
the DAC to precisely determine the required ADJ resistance value that would be needed in a final system that
does not have a DAC.
Figure 4-2 shows a schematic snippet of the DAC43701 portion of the TMAG5328EVM. The schematic snippet
below is also compatible with the DAC43701, which is the 10-bit version of the DAC43701. In addition, the
snippet is also compatible with the TPL1401, which is an 8-bit digital potentiometer device.
To select the DAC option for setting B
OP
, the DAC output must be connected to the ADJ pin, which is done by
the following steps:
• Do not populate resistor R7.
• Connect a jumper between the "DAC" (pin 1) and "ADJ" (pin 2) pins of header J3.
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6 TMAG5328 Evaluation Module SBAU376 – DECEMBER 2021
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