Q: What is the function of the INX pin on the MAX15108A? Should it be shorted to IN, as in the typical application schematic, or should it be low-pass filtered, as in the EVKIT?
A: IN is the input for the power train, while INX is the supply input for the analog circuitry. The two pins should be shorted together externally, with no low pass filter. They are shorted internally with a small resistor, so filtering IN with a large resistor/capacitor can cause a significant voltage difference during large input transients, such as start up, which can lead to erratic behavior and damage to the part.