I'm facing now a problem, namely that I have to measure analog signals in very rough industrial environment. The measured analog signal comes from a sensor over a long (5-10 meters) cable. The inputs must be protected agains EMI and ESD, and even a the case must be considered, that the 440V mains voltage is suddenly present on the inputs. So the inputs must be very high impedance inputs with lot's of protection.
The signal is a slow signal so the capacitance of the protection devices in not really important. But the leakage current should be as low as possible.
Does anybody have experience in that field? Any suggestion, links, books, tutorials are welcome.