Tri-state outputs: Can a three-state TTL output present three distinct states on its pin — logic LOW, logic HIGH, or a high-impedance (floating) state?

Introduction / Context:
Tri-state (three-state) outputs are essential for shared buses. By adding an enable control, the output driver can disconnect from the line, allowing multiple devices to share the same signal path without contention.

Given Data / Assumptions:

• TTL or CMOS devices with OE (output enable) pins.
• Bus-oriented systems where multiple devices must take turns driving a line.
• High-impedance state presents effectively no drive.

Concept / Approach:
With OE asserted, the output driver actively drives LOW or HIGH. With OE deasserted, both pull-up and pull-down devices are turned off, leaving the pin in a high-impedance state. External pull-ups/downs or bus keepers may define the idle level.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets specify three-state characteristics, including IOZ (leakage currents) and enable/disable timing parameters.

Why Other Options Are Wrong:

• “Only LOW/HIGH” ignores the high-Z mode.
• “Requires >6 V” is not part of three-state operation.
• “Only with open-collector” confuses passive pull-ups with active three-state drivers; they are different concepts.

Common Pitfalls:
Forgetting to include pull resistors or bus keepers; enabling two drivers simultaneously causing bus contention and potential damage.

Final Answer:
Yes — three-state outputs provide LOW, HIGH, or high-impedance.