CrossRoads:
Why not use a P-channel instead, sourcing current into a 10K resistor to Gnd.
When the P-channel opens up, the resistor pulls the analog pin low.Oherwise, post a schematic so we can see where this 48V is coming from.
I need to supply up to 10 amps (the load varies but can be as small as ~5 ohms). I'm controlling a variety of current hogging devices and I'm using a sort-of "multiplexing" system where I switch grounds on/off with N-channel MOSFETs and I switch V+ on/off with P-channel MOSFETs. I'm working under contract as a "consultant" and I can't provide too many specifics. I'm sorry - I know ambiguous questions get ambiguous answers but that's why I tried to ask a specific question regarding the reliability of zeners.
Basically, I am using the source-drain resistance of the MOSFET as a current-sense resistor. A crude measurement of the current is all that is necessary.