I have an input signal with falling time of about 100 ms.
You can see it on attached files.
This signal switch on/off about one time in 1 minutes.
Do you think that this long-term behaviour could damage the internal circuit?
From the input signal, I find the high level is nearly 6V, What's your power supply voltage of input side? I think that may cause some problems.
But for the long-term behaviour, it will not affect the internal circuit.
I don't know if the output will affect your system due to the second figure you showed. But it's true because at that time, your input signal is at the middle which is uncertain level for the input of ADuM1410.