Current controlled SPST

This component models a single pole, single throw switch. When the control current is greater than Ion, the switch has a resistance of Ron. When the control current is less than Ioff, the switch has a resistance of Roff. When the control current is in between Ion and Ioff, the resistance is between Ron and Roff and is a based on a smooth logarithmic function which is designed to assist convergence when the switch changes states.