74HCT251

The 74HCT251 is high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A.

The 74HCT251 is the logic implementations of single-pole 8-position switches with the state of three select inputs (S₀, S₁, S₂) controlling the switch positions. Assertion (Y) and negation (Y) outputs are both provided. The output enable input (OE) is active LOW. The logic function provided at the output, when activated, is: Y = OE.(I₀.S₀.S₁.S₂ + I₁.S₀.S₁.S₂ + + I₂.S₀.S₁.S₂ + I₃.S₀.S₁.S₂ + + I₄.S₀.S₁.S₂ + I₅.S₀.S₁.S₂ + + I₆.S₀.S₁.S₂ + I₇.S₀.S₁.S₂) Both outputs are in the high impedance OFF-state (Z) when the output enable input is HIGH, allowing multiplexer expansion by tying the outputs.