The exposed pad is connected to the substrate which, in this case, is the most
negative voltage, Vss. The exposed pad should be connected to Vss to enable
more efficient heat transfer and increase reliability. There is no
impact on switch performance if exposed pad is left unconnected but heat
dissipation will not be optimized. Connecting the exposed pad to anything other
than Vss potential may cause high current flow, affect the switch performance,
and the long-term reliability of the part.