...and one more:
In trying to calculate a new operating point for the TLV431 used to clamp the ADC voltage (the BeagleBone has 1.8V Analog inputs), I thought I'd check the existing operating point.
It doesn't look like ANY current is flowing through the exsiting regulator. If the schematic indicated values are correct (R1002=10K, R1003=1.5K, R1004=1K), that's 12500 ohms for the three in series, which puts 2.4V across the 2.5K of R1003/R1004 (2500R * 12V / 12500R = 2.4V). The TLV431 would have to be a battery for OV_REF to get to 3.1V. Unlike the LED issue, this can be easily fixed with value changes.
In trying to calculate a new operating point for the TLV431 used to clamp the ADC voltage (the BeagleBone has 1.8V Analog inputs), I thought I'd check the existing operating point.
It doesn't look like ANY current is flowing through the exsiting regulator. If the schematic indicated values are correct (R1002=10K, R1003=1.5K, R1004=1K), that's 12500 ohms for the three in series, which puts 2.4V across the 2.5K of R1003/R1004 (2500R * 12V / 12500R = 2.4V). The TLV431 would have to be a battery for OV_REF to get to 3.1V. Unlike the LED issue, this can be easily fixed with value changes.