The UM3156 is an advanced CMOS analog switch fabricated with silicon gate CMOS technology. It achieves very low propagation delay and RDS(ON) resistances while maintaining CMOS low power dissipation. These make it ideal for portable and battery power applications. The switch conducts signals within power rails equally well in both directions when on, and blocks up to the power supply level when off. Break-before-make is guaranteed. The select pin has over-voltage protection that allows voltages above VCC, up to 6.5V to be present on the pin without damage or disruption of operation of the part, regardless of the operating voltage. The UM3156 can maintain low power consumption for rail-to-rail signaling as long as the control signal input is held at a level that is greater than VIH minimum and less than VIL maximum by improving the control circuitry input buffer. so the part can be used in mixed voltage rail environments, especially services the mobile handset applications very well allowing for the direct interface with baseband processor general purpose I/Os, and it is no longer necessary to have the control input equal to VCC to maintain low power consumption