How to protect input against both ESD and reverse polarity?
If the idea is to protect the diode, one could put a TVS diode with a voltage much higher than anything that might be put on the inputs, like something that would clamp more than 40 or 100V. There are many TVS diodes built specifically for handling ESD and have much higher 'knee' voltages. The diode would not turn on if the polarity were reversed, but would turn on during an ESD event. This would protect the reverse polarity diode. 







simulate this circuit &ndash; Schematic created using CircuitLab

Another way that less lossy would to use a pmosfet for reverse polarity protection.







simulate this circuit