TMUX7612: mux status when unpowered

The switch itself is open, but there are clamping diodes to the power rails, so the absolute maximum ratings forbid voltages above V_DD + 0.5 V.

Hey Dan,

You'll likely turn the device on if you apply a signal when the supply is off. We can't guarantee anything since it's technically using the device outside the specs but you'll end up backpowering an internal FET gate that will turn on the source to drain path. So technically if there is no signal on the S/D pins the channel would be off but in the scenario where it matter where a signal is on the source/drain, then the devices signal path would be on

 
If you want a 4ch 1:1 device that can support powered-off protection (isolating the input to output when supply =0V) take a look at  the TMUX741xF

Thanks,
Rami