TC74VHC138 is an advanced high speed CMOS 3-to-8 DECODER fabricated with silicon gate C2MOS technology. It achieves the high speed operation similar to equivalent Bipolar Schottky TTL while maintaining the CMOS low power dissipation. When the device is enabled, 3 Binary Select inputs (A, B and C) determine which one of the outputs ( Y0 - 7 When enable input G1 is held low or eitherY ) will go low. G2A or G2B is held high, decoding function is inhibited and all outputs go high. G1, G2A , and G2B inputs are provided to ease cascade connection and for use as an address decoder for memory systems. An input protection circuit ensures that 0 to 5.5 V can be applied to the input pins without regard to the supply voltage. This device can be used to interface 5 V to 3 V systems and two supply systems such as battery back up. This circuit prevents device destruction due to mismatched supply and input voltages.
The TC74VHC138 is an advanced high‑speed CMOS 3‑to‑8 line decoder that uses silicon gate C2MOS technology. It provides three binary select inputs (A, B, C) to activate one of eight outputs, with enable inputs G1, G2A, and G2B for cascade connections and address decoding. Features include a typical propagation delay of 5.7 ns, low power dissipation (4 µA max), high noise immunity, and input protection for 0‑5.5 V.
The device is offered in four package types (SOP16, SOL16, TSSOP16, VSSOP16) with typical weights ranging from 0.02 g to 0.18 g. Electrical characteristics cover absolute maximum ratings, operating ranges (2 V‑5.5 V supply, –40 °C‑85 °C temperature), and detailed DC/AC parameters. The datasheet also includes usage restrictions and compliance notes.
| Typical propagation delay (tpd) | 5.7 ns |
|---|---|
| Operating voltage range (VCC) | 2.0 V to 5.5 V |
| Input protection voltage range | 0 V to 5.5 V |
| Pin and function compatibility | 74ALS138 |
It is a 3‑to‑8 line decoder that selects one of eight outputs based on three binary inputs.
The supply voltage range is –0.5 V to 7.0 V.
The device operates from –40 °C to 85 °C.