Gates: Tri-State Buffer

A tri-state buffer acts like a valve: controls flow of current.

Input: 2 bits

Output: 1 bit

simplified:

active-high

Truth table:

Input

Output

Input

Output

c

x

z

c

z

0

0

Z

no current

0

Z

0

1

Z

1

x

1

0

0

1

1

1

active-low

Input

Output

When c = 1, the output is equal to x, otherwise there is no output.

c

z

Active-low: Output is x when c = 0.

0

x

1

Z