TMUX4157N 2:1 SPDT Negative Voltage Switch Texas Instruments TMUX4157N 2:1 Single-Pole Double-Throw (SPDT) Negative Voltage Switch supports a negative supply rail only. The supply voltage can range from -4V to -12V and the device supports bidirectional analog and digital signals on the source (Sx) and drain (D) pins ranging from GND to VSS. The state of the select pin (SEL) controls which of the two sources pins are connected to the drain pin.