There are two boards A and B for communication. The length of communication line is about 3.5 meters ~4M. TPD1E10B06 is used for ESD protection of signals. The current between the pins of ESD devices and the ground is about 4mA measured by the current probe clamp of oscilloscope.
However, the data sheet of TPD1E10B06 indicates that the normal working current should be less than 100nA.By replacing the TPD1E10B06 device and removing the 3.5m communication line, the oscilloscope captures a current of 4mA.Schematic diagram and test current waveform are shown below.Is that normal?Please help to analyze the reason