Tool/software:
I am using an LMR51603XDBVR with input diodes to VIN. This allows either of two power sources, nominal 48V, to power the circuit. Two diodes with anodes to the voltage supply and cathode to the regulator.
One has a voltage divider in parallel to the diode input to a 110kΩ voltage divider to an input to a logic gate (48V -> 100kΩ -> gate logic at 4.4V -> 10kΩ -> GND). The problem I have is the diode has reverse leakage when the other power supply is on and the input for this side is open. The 110kΩ should pull it to ground, but I find about 45V at the diode anode.
This condition exists with this regulator, but not with either an AP7387 or ZXTR2105 linear regulator. Nominal load is 20mA and neither of those will support that at 48V (ignore the AP7387 data sheet, that is not accurate).
I have tried increasing the 5V load from 20 mA to 50mA & 100mA, but there is no change. The diode is a Schottky BAS70-00, but I had similar results with a BAS16W.
The circuit is from Figure 8.1 of the LMR51603 data sheet. I have tried a 4.7µF cap for CIN with no change.
I also tried a 1µH inductor in series with the diode with no change either. The problem exists with lower input at 42V & 32V.