Under what max. tolerable current
your clamp internal diodes on S1through S8 inputs will provide
protection of that inputs from overvoltage? Refer to Absolute maximum
("Overvoltages at IN, S or D will be clamped by internal diodes" and so on....)
The only time there should be current flowing when the switch is open is if
they exceed the power supplies. (Overvoltages at source or drain will be
clamped by internal diodes).
Basically it will look like a diode up and a diode down when open.
Therefore you need to ensure that the source and drains are lower than Vdd and
To be absolutely safe and well within absolute max ratings, you should use
series resistors of a few Kohms to limit your currents to 10 mA.