Part Number:LM2941C
I am trying to determine the behaviour of LM2941SX LDO's if they are back powered from the output sides.
The particular situation I have is where there are two of these regulators, one set for 5V out and the other set for 12V out.
In the circuits these are driving, there are parasitic IC diodes in several mixed digital/analog chips that point from the digital 5V supply pins to the analog 12V supply pins.
If power from the 5V side is applied first and the input to the 12V side remains off, the parasitic diodes in the powered IC's will forward bias from the 5V side and try to drive the 12V supply pins to about 4.3V.
At this point, there will be about 4.3V applied to the LDO output when the input voltage is very nearly zero (in the circuit I'm looking at, the 5V input is always present, bu the 12V LDO input may not be energized or may actually be held at ground).
Are there any reverse body diode elements or other features that would allow significant current to flow into the output of the LDO if the input were either floating or held near ground through a low impedance?
For instance, is there a parasitic diode between the output and input?
Is there a mechanism where current would flow into the output and into the ground lead?
