The VHC157 is an advanced high speed CMOS Quad 2-Channel Multiplexer fabricated with silicon gate CMOS technology. It achieves the high speed operation similar to equivalent Bipolar Schottky TTL while maintaining the CMOS low power dissipation. It consists of four 2-input digital multiplexers with common select and enable inputs. When the ENABLE# input is held "H" level, selection of data is inhibited and all the outputs become "L" level. The SELECT decoding determines whether the I0xor I1xinputs get routed to their corresponding outputs. An Input protection circuit ensures that 0V to 7V can be applied to the input pins without regard to the supply voltage. This device can be used to interface 5V to 3V systems and on two supply systems such as battery back up. This circuit prevents device destruction due to mismatched supply and input voltages.