74VHC138

The 74VHC138 is an advanced high speed CMOS 3-to-8 decoder/demultiplexer 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.

When the 74VHC138 is enabled, 3 binary select inputs (A0, A1 and A₂) determine which one of the outputs (O₀O₇) will go LOW. When enable input E₃ is held LOW or either E₁ or E₂ is held HIGH, decoding function is inhibited and all outputs go HIGH. E₃, E₁ and E₂ inputs are provided to ease cascade connection and for use as an address decoder for memory systems. 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 two supply systems of the 74VHC138 such as battery back up. This circuit prevents device destruction due to mismatched supply and input voltages.