Logic circuits

What is the third state that the output of a tri-state buffer can take?

  1. AOutputting half the supply voltage
  2. BRapidly alternating between 0 and 1
  3. CDisconnecting the output into a high-impedance state
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Answer: C. Disconnecting the output into a high-impedance state

Besides 0 and 1, a tri-state buffer can enter a high-impedance (Hi-Z) state in which its output is disconnected from the circuit. When several circuits share one bus, putting the outputs of unused circuits into high impedance prevents signal conflicts.

  • A. It is not a state that continuously outputs an intermediate voltage.
  • B. It is not an oscillating state.
  • C. Correct. The third state is high impedance.
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