The STG3155 is a high-speed CMOS low voltage single analog S.P.D.T. (Single Pole Dual Throw) switch or 2:1 Multiplexer /Demultiplexer switch fabricated in silicon gate C2MOS technology. It is designed to operate from 1.65V to 4.3V, making this device ideal for portable applications. The device offers very low ON-Resistance (<0.5) at VCC = 4.3V. The SEL inputs are provided to control the switch. The switch S1 is ON (they are connected to common Ports Dn) when the SEL input is held high and OFF (high impedance state exists between the two ports) when SEL is held low; the switch S2 is ON (it is connected to common Port D) when the SEL input is held low and OFF (high impedance state exists between the two ports) when SEL is held high.