SN74LVC2G66: Junction Temp

Hi Brian

Please see this FAQ:
[FAQ] How to Calculate the Max Junction Temperature of an Analog Switch/Multiplexer

There's a link at the bottom for an excel that allows you to put in your conditions and it will solve the junction temperature for you. The excel asks for max conditions but if you're looking for your conditions junction temperature you can put it in the voltage, current, etc that the mux will actually see in your system.
Let me know if you have any questions. 

Thanks!
Rami