The MC74VHCT157A is an advanced high speed CMOS quad 2-channel multiplexer fabricated with silicon gate CMOS technology. It achieves high speed operation similar to equivalent Bipolar Schottky TTL while maintaining CMOS low power dissipation. It consists of four 2-input digital multiplexers with common select (S) and enable (E) inputs. When E is held High, selection of data is inhibited and all the outputs go Low. The select decoding determines whether the A or B inputs get routed to the corresponding Y outputs. The VHCT inputs are compatible with TTL levels. This device can be used as a level converter for interfacing 3.3 V to 5.0 V because it has full 5.0 V CMOS level output swings. The VHCT157A input structures provide protection when voltages between 0 V and 5.5 V are applied, regardless of the supply voltage. The output structures also provide protection when VCC = 0 V. These input and output structures help prevent device destruction caused by supply voltage-input/output voltage mismatch, battery backup, hot insertion, etc.