Question

The logical equation of tri-state buffer is \[ (E=\text{enable},\;Z=\text{high impedance}) \]

• A. \[ Y=E'Z+EX \]
• B. \[ Y=E'Z'+EX' \]
• C. \[ Y=Z'+EX \]
• D. \[ Y=EZ+X \]

Hint:

A tri-state buffer acts as a switch controlled by the enable signal.

Answer 1

The Correct Option is A

Concept: A tri-state buffer has three output states: \[ 0,\;1,\;Z \] where \(Z\) denotes high impedance.

Step 1: Consider enable input.
When \[ E=1 \] the output follows the input. \[ Y=X \]

Step 2: Consider disable condition.
When \[ E=0 \] the output becomes \[ Y=Z \]

Step 3: Form logical expression.
\[ Y=E'Z+EX \] \[ \boxed{Y=E'Z+EX} \]