The Fairchild Switch FSTU3125 provides four high-speed CMOS TTL-compatible bus switches. The low On Resistance of the switch allows inputs to be connected to outputs without adding propagation delay or generating additional ground bounce noise. The A and B Ports are protected against undershoot to support an extended range to 2.0V below ground. Fairchild's integrated Undershoot Hardened Circuit (UHC) senses undershoot at the I/O and responds by preventing voltage differentials from developing and turning the switch on.