Glossary Definition for Three-State

Glossary Term: Three-State 


A three-state, or Tri-State™, output has three electrical states: One, zero, and "Hi-Z," or "open." The hi-Z state is a high-impedance state in which the output is disconnected, leaving the signal open, to be driven by another device (or to be pulled up or down by a resistor provided to prevent an undefined state).

High-impedance schemes such as three-state are commonly used for a bus, in which several devices can be selected to drive the bus.

Tri-State™ is a trademark of National Semiconductor.

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