Hi alromh87,
I am an electronic design engineer with 15+ years experience. I tried to find schematics for my monotronics board several years ago but have given up in despair. The link provided on the monotronics page (http://reprap.org/wiki/Monotronics#Alternatives) has never worked for me, and appears to be a link used to upload the schematic. If you have a schematic, I would be very grateful to have a look and try and help figure out the MFK component...
While I have not had the time to reverse engineer the PCB, my current guesses/hypotheses are;
1) A resistor array to provide some level of current limiting on communication signals - though judging by the rest of the monotronics board, I would be surprised if this had been included.
2) A voltage regulator of some sort - depending on the needs of the DS2762A
3) Given that the DS2762A is actually intended for lithium ion battery monitoring and seems an unusual choice/ overkill / (inexperienced?) for a simple temperature sensor, the MFK could be anything...