Note on Tri-state Devices
We talked about the two binary states. We also talked about enabling
outputs. Effectively this gives a third state called the off or high
impedance state. We refer to this as tri-state logic
Consider the tri-state buffer shown:
Tri-state logic presents the designer with a very useful ability: can tie
multiple outputs together provided only one is driven at any one time
(bussing)
Bus contention occurs if more than one output is enabled at any one
time
University of KwaZulu-Natal 1
12-1
ENEL2EBH2 2010
, Note on Tri-state Devices
Tri-state buffer options:
University of KwaZulu-Natal 2
12-2
ENEL2EBH2 2010
We talked about the two binary states. We also talked about enabling
outputs. Effectively this gives a third state called the off or high
impedance state. We refer to this as tri-state logic
Consider the tri-state buffer shown:
Tri-state logic presents the designer with a very useful ability: can tie
multiple outputs together provided only one is driven at any one time
(bussing)
Bus contention occurs if more than one output is enabled at any one
time
University of KwaZulu-Natal 1
12-1
ENEL2EBH2 2010
, Note on Tri-state Devices
Tri-state buffer options:
University of KwaZulu-Natal 2
12-2
ENEL2EBH2 2010
