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Power supplied to the PD_12 and the BAT_IN
PD_12 supply set the 12V
Checked the voltage at PD_12, and it is correctly 12V
BAT_IN set to voltages ranging from 9V to 15V
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Restarting the test, both states produced a 0V output at the comparator.
Afterward, restarted the test but the output of the comparator outputted a voltage less than but proportional to the BAT_IN. For example, with the power supply set to 9V the comparator output was around 6V, with 13V around 7.5V and so on.
Next steps: the validation plan makes sense according to a schematic, will check the physical hardware.