Elementary SPICE Components
XXXXXXX syntax in the general form describing elementary SPICE components is to dominate a user choosen alpha-numeric identifier (e.g.
RXXXXXXX could stand for
Voltage And Current Controlled Switches
Two types of switches in SPICE, voltage and current controlled. They are not ideal switches, and are modelled with a finite on and off resistance, as well as finite turn on and off times. However, you can usually set these to the extremes so that they act almost like an ideal switch, in relation to everything else in your circuit.
They are great for seeing what effect a short with have on your circuit (e.g. shorting out one LED in a string of LEDs controlled by a constant-current driver).
SPICE prefix for switches is S.
The general form for a switch is:
SXXXXXXX N+ N- NC+ NC- MODEL <ON><OFF> WYYYYYYY N+ N- VNAM MODEL <ON><OFF>
The most basic syntax to create a voltage-controlled switch is:
.model VSW SW()